feat(效能分析): 轨迹流转图时间轴支持工作日/自然天切换

- flow 接口加 mode 参数，workdays 模式把时间偏移换算为排除周末/节假日的工作小时
- 轨迹流转图的横轴随顶部按钮(自然天/工作日)切换，休息日被压缩
- 按钮切换自动重新请求 flow

frontend/src/pages/admin/AnalyticsDashboard.tsx

@@ -127,8 +127,9 @@ export default function AnalyticsDashboard() {
     const q: FlowQuery = {};
     if (productSns.length) q.product_sns = productSns;
     if (specModels.length) q.spec_models = specModels;
+    q.mode = totalDaysMode;   // 自然天 / 工作日，控制轨迹流转图时间口径
     return q;
-  }, [productSns, specModels]);
+  }, [productSns, specModels, totalDaysMode]);
 
   // ─── 能力图谱（需选择人员才发起） ──
   const loadCapability = useCallback(async () => {

frontend/src/services/analyticsApi.ts

@@ -103,6 +103,7 @@ export interface CapabilityQuery {
 export interface FlowQuery {
   product_sns?: string[];
   spec_models?: string[];
+  mode?: "natural" | "workdays";
 }
 
 // ============================================================
@@ -123,6 +124,7 @@ export async function fetchFlowData(query: FlowQuery): Promise<FlowResponse> {
   const params: Record<string, string> = {};
   if (query.product_sns?.length) params.product_sns = query.product_sns.join(",");
   if (query.spec_models?.length) params.spec_models = query.spec_models.join(",");
+  if (query.mode) params.mode = query.mode;
   const { data } = await api.get<FlowResponse>("/analytics/flow", { params });
   return data;
 }