feat: 管理看板全面改版 — 增强可读性 + 填充空白区域

后端增强:
  - DashboardStats 新增 tasks_rejected, tasks_rework, unread_notifications
  - 新增 GET /dashboard/recent-activity 最近动态端点
  - 关联 Task + Product 表返回完整动态信息

前端改版 (AdminDashboard.tsx):
  - 4 张概览卡片: 产品流转 | 任务状态 | 品质通知 | 完成率
  - 每张卡片含进度条(百分比标注) + 中文说明
  - SVG 环形图展示任务完成率
  - 最近流转动态时间线 (8条)
  - 快捷入口: 创建产品/任务管理/打印配置/扫码干活
  - 底部说明卡片解释"产品 vs 任务"的区别
  - 响应式网格填满全屏, 无空白区域

frontend/src/pages/admin/AdminDashboard.tsx

@@ -1,80 +1,261 @@
 import { useEffect, useState } from "react";
-import { Package, ClipboardList, Loader2, AlertCircle } from "lucide-react";
-import { fetchDashboardStats, type DashboardStats } from "../../services/dashboardApi";
+import {
+  Package, ClipboardList, Bell, TrendingUp, AlertTriangle,
+  RefreshCw, Loader2, AlertCircle, Plus, ArrowRight,
+} from "lucide-react";
+import { useNavigate } from "react-router-dom";
+import {
+  fetchDashboardStats, fetchRecentActivity,
+  type DashboardStats, type RecentActivity,
+} from "../../services/dashboardApi";
 
-function StatCard({
-  label,
-  total,
-  pending,
-  progress,
-  done,
-  icon: Icon,
-}: {
-  label: string;
-  total: number;
-  pending: number;
-  progress: number;
-  done: number;
-  icon: React.ComponentType<{ className?: string }>;
-}) {
+// ─── 小卡片 ───────────────────────────────────────────────
+function MiniStat({ value, label, color }: { value: number; label: string; color: string }) {
   return (
-    <div className="rounded-xl bg-white p-5 shadow-sm">
-      <div className="mb-4 flex items-center gap-2">
-        <Icon className="h-5 w-5 text-blue-600" />
-        <h3 className="font-semibold text-gray-800">{label}</h3>
-        <span className="ml-auto text-2xl font-bold text-gray-800">{total}</span>
+    <div className="text-center">
+      <span className={`text-xl font-bold ${color}`}>{value}</span>
+      <p className="text-[11px] text-gray-400">{label}</p>
+    </div>
+  );
+}
+
+// ─── 进度条 ───────────────────────────────────────────────
+function ProgressBar({ a, b, c, total, labels }: {
+  a: number; b: number; c: number; total: number;
+  labels: [string, string, string];
+}) {
+  if (total === 0) return <div className="py-4 text-center text-xs text-gray-400">暂无数据</div>;
+  const pct = (n: number) => Math.round((n / total) * 100);
+  const segs = [
+    { n: a, color: "bg-amber-400", label: labels[0] },
+    { n: b, color: "bg-blue-500", label: labels[1] },
+    { n: c, color: "bg-emerald-500", label: labels[2] },
+  ].filter(s => s.n > 0);
+
+  return (
+    <div>
+      <div className="flex h-3 overflow-hidden rounded-full bg-gray-100">
+        {segs.map((s, i) => (
+          <div key={i} className={`${s.color} transition-all duration-500`}
+            style={{ width: `${(s.n / total) * 100}%` }} />
+        ))}
       </div>
-      <div className="flex h-2 overflow-hidden rounded-full bg-gray-100">
-        {pending > 0 && (
-          <div className="bg-yellow-400" style={{ width: `${(pending / Math.max(total, 1)) * 100}%` }} />
-        )}
-        {progress > 0 && (
-          <div className="bg-blue-500" style={{ width: `${(progress / Math.max(total, 1)) * 100}%` }} />
-        )}
-        {done > 0 && (
-          <div className="bg-green-500" style={{ width: `${(done / Math.max(total, 1)) * 100}%` }} />
-        )}
-      </div>
-      <div className="mt-3 flex gap-4 text-xs text-gray-500">
-        <span className="flex items-center gap-1"><span className="inline-block h-2 w-2 rounded-full bg-yellow-400" />待处理 {pending}</span>
-        <span className="flex items-center gap-1"><span className="inline-block h-2 w-2 rounded-full bg-blue-500" />进行中 {progress}</span>
-        <span className="flex items-center gap-1"><span className="inline-block h-2 w-2 rounded-full bg-green-500" />已完成 {done}</span>
+      <div className="mt-2 flex flex-wrap gap-3 text-xs text-gray-500">
+        {segs.map((s, i) => (
+          <span key={i} className="flex items-center gap-1">
+            <span className={`inline-block h-2 w-2 rounded-full ${s.color}`} />
+            {s.label} {s.n}（{pct(s.n)}%）
+          </span>
+        ))}
       </div>
     </div>
   );
 }
 
+// ─── 动态条目 ─────────────────────────────────────────────
+function ActivityItem({ a }: { a: RecentActivity }) {
+  const iconMap: Record<string, string> = {
+    "创建任务": "📋", "确认接收": "✅", "完成任务": "🏁", "完工转交": "🔄",
+    "品质驳回": "❌", "结束分支": "🛑", "撤回转交": "↩️",
+  };
+  return (
+    <div className="flex items-start gap-3 border-b border-gray-50 py-2.5 last:border-0">
+      <span className="mt-0.5 text-base">{iconMap[a.action] || "📌"}</span>
+      <div className="min-w-0 flex-1">
+        <div className="flex items-baseline gap-2">
+          <span className="text-sm font-medium text-gray-700">{a.action}</span>
+          <span className="truncate text-xs text-gray-500">{a.task_name}</span>
+        </div>
+        <div className="mt-0.5 flex items-center gap-2 text-[11px] text-gray-400">
+          <span>{a.operator}</span>
+          <span>·</span>
+          <span className="font-mono">{a.product_sn.slice(0, 8)}…</span>
+          <span className="ml-auto">{a.time}</span>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+// ─── 主组件 ───────────────────────────────────────────────
 export default function AdminDashboard() {
   const [stats, setStats] = useState<DashboardStats | null>(null);
+  const [activity, setActivity] = useState<RecentActivity[]>([]);
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
+  const navigate = useNavigate();
 
   useEffect(() => {
-    fetchDashboardStats()
-      .then(setStats)
+    Promise.all([
+      fetchDashboardStats(),
+      fetchRecentActivity(8),
+    ])
+      .then(([s, a]) => { setStats(s); setActivity(a); })
       .catch(() => setError("加载统计数据失败，请确认后端已启动"))
       .finally(() => setLoading(false));
   }, []);
 
+  // ── 加载态 ──
   if (loading) {
-    return <div className="flex items-center justify-center py-20"><Loader2 className="h-8 w-8 animate-spin text-blue-500" /></div>;
+    return (
+      <div className="flex items-center justify-center py-20">
+        <Loader2 className="h-8 w-8 animate-spin text-blue-500" />
+      </div>
+    );
   }
 
-  if (error) {
-    return <div className="flex items-center gap-2 rounded-lg border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700"><AlertCircle className="h-4 w-4" />{error}</div>;
+  // ── 错误态 ──
+  if (error || !stats) {
+    return (
+      <div className="flex items-center gap-2 rounded-lg border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700">
+        <AlertCircle className="h-4 w-4" />{error || "数据为空"}
+      </div>
+    );
   }
 
-  if (!stats) return null;
-
   return (
-    <div>
-      <div className="mb-6">
-        <h2 className="text-xl font-bold text-gray-800">全局生产概览</h2>
-        <p className="mt-1 text-sm text-gray-500">PC端与移动端共享同一后台数据</p>
+    <div className="space-y-6">
+      {/* ═══ 页头 ═══ */}
+      <div className="flex items-center justify-between">
+        <div>
+          <h2 className="text-xl font-bold text-gray-800">📊 生产管理看板</h2>
+          <p className="mt-0.5 text-sm text-gray-400">
+            产品 = 物理实体（身份证）｜ 任务 = 工序节点（流转步骤）
+          </p>
+        </div>
+        <button onClick={() => window.location.reload()}
+          className="flex items-center gap-1 rounded-lg px-3 py-1.5 text-xs text-gray-500 hover:bg-gray-100">
+          <RefreshCw className="h-3.5 w-3.5" />刷新
+        </button>
       </div>
-      <div className="grid gap-5 md:grid-cols-2">
-        <StatCard label="产品统计" total={stats.products_total} pending={stats.products_pending} progress={stats.products_in_progress} done={stats.products_completed} icon={Package} />
-        <StatCard label="任务统计" total={stats.tasks_total} pending={stats.tasks_pending} progress={stats.tasks_in_progress} done={stats.tasks_completed} icon={ClipboardList} />
+
+      {/* ═══ 第1行：4 张概览卡片 ═══ */}
+      <div className="grid gap-4 sm:grid-cols-2 xl:grid-cols-4">
+        {/* 产品流转 */}
+        <div className="rounded-xl bg-white p-5 shadow-sm">
+          <div className="mb-3 flex items-center gap-2">
+            <Package className="h-5 w-5 text-blue-600" />
+            <h3 className="text-sm font-semibold text-gray-700">📦 产品流转</h3>
+          </div>
+          <p className="text-3xl font-bold text-gray-800">{stats.products_total}<span className="text-sm font-normal text-gray-400"> 个</span></p>
+          <p className="mb-3 text-[11px] text-gray-400">已登记的物理产品数量</p>
+          <ProgressBar a={stats.products_pending} b={stats.products_in_progress} c={stats.products_completed}
+            total={stats.products_total} labels={["待流转", "流转中", "已完成"]} />
+        </div>
+
+        {/* 任务状态 */}
+        <div className="rounded-xl bg-white p-5 shadow-sm">
+          <div className="mb-3 flex items-center gap-2">
+            <ClipboardList className="h-5 w-5 text-purple-600" />
+            <h3 className="text-sm font-semibold text-gray-700">📋 任务状态</h3>
+          </div>
+          <p className="text-3xl font-bold text-gray-800">{stats.tasks_total}<span className="text-sm font-normal text-gray-400"> 个</span></p>
+          <p className="mb-3 text-[11px] text-gray-400">产品下所有工序任务汇总</p>
+          <ProgressBar a={stats.tasks_pending} b={stats.tasks_in_progress} c={stats.tasks_completed}
+            total={stats.tasks_total} labels={["待接收", "进行中", "已完成"]} />
+        </div>
+
+        {/* 品质 & 通知 */}
+        <div className="rounded-xl bg-white p-5 shadow-sm">
+          <div className="mb-4 flex items-center gap-2">
+            <AlertTriangle className="h-5 w-5 text-orange-600" />
+            <h3 className="text-sm font-semibold text-gray-700">⚠️ 品质 & 通知</h3>
+          </div>
+          <div className="grid grid-cols-2 gap-4">
+            <div className="rounded-lg bg-red-50 p-3 text-center">
+              <p className="text-2xl font-bold text-red-600">{stats.tasks_rejected + stats.tasks_rework}</p>
+              <p className="text-[11px] text-red-500">驳回/返工</p>
+            </div>
+            <div className="rounded-lg bg-blue-50 p-3 text-center">
+              <p className="text-2xl font-bold text-blue-600">{stats.unread_notifications}</p>
+              <p className="text-[11px] text-blue-500">未读通知</p>
+            </div>
+          </div>
+          <div className="mt-3 flex justify-around border-t border-gray-100 pt-3">
+            <MiniStat value={stats.tasks_rejected} label="已驳回" color="text-red-600" />
+            <MiniStat value={stats.tasks_rework} label="返工中" color="text-orange-600" />
+            <MiniStat value={stats.unread_notifications} label="未读消息" color="text-blue-600" />
+          </div>
+        </div>
+
+        {/* 完成率 */}
+        <div className="rounded-xl bg-white p-5 shadow-sm">
+          <div className="mb-3 flex items-center gap-2">
+            <TrendingUp className="h-5 w-5 text-emerald-600" />
+            <h3 className="text-sm font-semibold text-gray-700">✅ 流转完成率</h3>
+          </div>
+          <div className="flex items-end gap-4">
+            <p className="text-3xl font-bold text-emerald-600">
+              {stats.tasks_total > 0 ? Math.round((stats.tasks_completed / stats.tasks_total) * 100) : 0}%
+            </p>
+            <p className="text-sm text-gray-400">{stats.tasks_completed}/{stats.tasks_total} 已完成</p>
+          </div>
+          {/* 简易环形图 */}
+          <div className="mt-4 flex justify-center">
+            <svg viewBox="0 0 100 100" className="h-20 w-20 -rotate-90">
+              <circle cx="50" cy="50" r="40" fill="none" stroke="#f3f4f6" strokeWidth="10" />
+              <circle cx="50" cy="50" r="40" fill="none" stroke="#10b981" strokeWidth="10"
+                strokeDasharray={`${stats.tasks_total > 0 ? (stats.tasks_completed / stats.tasks_total) * 251 : 0} 251`}
+                strokeLinecap="round" />
+            </svg>
+          </div>
+        </div>
+      </div>
+
+      {/* ═══ 第2行：最近动态 + 快捷入口 ═══ */}
+      <div className="grid gap-4 lg:grid-cols-3">
+        {/* 最近动态 */}
+        <div className="rounded-xl bg-white p-5 shadow-sm lg:col-span-2">
+          <div className="mb-3 flex items-center justify-between">
+            <h3 className="text-sm font-semibold text-gray-700">🕐 最近流转动态</h3>
+            <span className="text-[11px] text-gray-400">最新 8 条</span>
+          </div>
+          {activity.length === 0 ? (
+            <div className="py-8 text-center text-sm text-gray-400">暂无流转记录</div>
+          ) : (
+            <div className="divide-y divide-gray-50">
+              {activity.map((a, i) => <ActivityItem key={i} a={a} />)}
+            </div>
+          )}
+        </div>
+
+        {/* 快捷入口 */}
+        <div className="rounded-xl bg-white p-5 shadow-sm">
+          <h3 className="mb-4 text-sm font-semibold text-gray-700">⚡ 快捷入口</h3>
+          <div className="space-y-2">
+            <button onClick={() => navigate("/admin/products")}
+              className="flex w-full items-center justify-between rounded-lg bg-blue-50 px-4 py-3 text-left text-sm font-medium text-blue-700 hover:bg-blue-100 transition-colors">
+              <span className="flex items-center gap-2"><Plus className="h-4 w-4" />创建产品</span>
+              <ArrowRight className="h-4 w-4" />
+            </button>
+            <button onClick={() => navigate("/admin/tasks")}
+              className="flex w-full items-center justify-between rounded-lg bg-purple-50 px-4 py-3 text-left text-sm font-medium text-purple-700 hover:bg-purple-100 transition-colors">
+              <span className="flex items-center gap-2"><ClipboardList className="h-4 w-4" />任务管理</span>
+              <ArrowRight className="h-4 w-4" />
+            </button>
+            <button onClick={() => navigate("/admin/print-config")}
+              className="flex w-full items-center justify-between rounded-lg bg-amber-50 px-4 py-3 text-left text-sm font-medium text-amber-700 hover:bg-amber-100 transition-colors">
+              <span className="flex items-center gap-2">🖨️ 打印配置</span>
+              <ArrowRight className="h-4 w-4" />
+            </button>
+            <button onClick={() => navigate("/scan")}
+              className="flex w-full items-center justify-between rounded-lg bg-emerald-50 px-4 py-3 text-left text-sm font-medium text-emerald-700 hover:bg-emerald-100 transition-colors">
+              <span className="flex items-center gap-2">📱 扫码干活</span>
+              <ArrowRight className="h-4 w-4" />
+            </button>
+          </div>
+
+          {/* 说明卡片 */}
+          <div className="mt-5 rounded-lg bg-gray-50 p-3">
+            <p className="text-[11px] leading-relaxed text-gray-500">
+              <strong>💡 怎么理解？</strong><br />
+              一个<strong className="text-gray-700">产品</strong>从创建到入库，会经过多道
+              <strong className="text-gray-700">工序</strong>（装配→接线→质检…）。
+              每道工序就是一个<strong className="text-gray-700">任务</strong>，由不同工人完成。
+              所以任务数 ≥ 产品数是正常的。
+            </p>
+          </div>
+        </div>
       </div>
     </div>
   );