feat(borrow): 借库审批补「完结」能力（对齐出库 status=4）

- mark_completed 改为 1→4 已完结（真正扫码借出完成仍为 status=3）
- 前端审批页新增「已完结」筛选项与状态映射；审批信息列对 3/4 显示审批人

inventory-web/src/views/borrow/approval/index.vue

@@ -10,6 +10,7 @@
         <el-radio-button :label="1">已通过</el-radio-button>
         <el-radio-button :label="2">已驳回</el-radio-button>
         <el-radio-button :label="3">已完成</el-radio-button>
+        <el-radio-button :label="4">已完结</el-radio-button>
       </el-radio-group>
       <el-button type="primary" :icon="Refresh" @click="fetchData">刷新</el-button>
     </div>
@@ -108,7 +109,7 @@
               <el-icon style="margin-left: 4px; cursor: pointer;"><Warning /></el-icon>
             </el-tooltip>
           </template>
-          <template v-else-if="row.status === 3">
+          <template v-else-if="row.status === 3 || row.status === 4">
             <span style="color: #909399;">{{ getApproverName(row.actual_approver_id) }}</span>
           </template>
           <span v-else style="color: #c0c4cc;">-</span>
@@ -254,14 +255,14 @@ const userNameCache = ref<Record<number, string>>({})
 // --- 工具函数 ---
 const statusText = (status: number) => {
   const map: Record<number, string> = {
-    0: '待审批', 1: '已通过', 2: '已驳回', 3: '已完成'
+    0: '待审批', 1: '已通过', 2: '已驳回', 3: '已完成', 4: '已完结'
   }
   return map[status] ?? '-'
 }
 
 const statusTagType = (status: number) => {
   const map: Record<number, string> = {
-    0: 'warning', 1: 'success', 2: 'danger', 3: 'info'
+    0: 'warning', 1: 'success', 2: 'danger', 3: 'info', 4: 'info'
   }
   return map[status] ?? 'info'
 }