fix: EmployeeSelector 真实API查询+跨页选中持久

frontend/src/views/module_payment/institution/components/EmployeeSelector.vue

@@ -25,7 +25,7 @@
       <div class="employee-selector__tabs">
         <el-tabs v-model="activeTab" @tab-change="handleTabChange">
           <el-tab-pane label="全部" name="all" />
-          <el-tab-pane label="已选 ({{ selectedIds.length }}人)" name="selected" />
+          <el-tab-pane label="已选 ({{ internalSelectedIds.length }}人)" name="selected" />
         </el-tabs>
       </div>