feat(admin): 添加账号批量调度开关功能

- 后端：支持批量更新账号的 schedulable 字段
  - 在 BulkUpdateAccountsRequest 中添加 schedulable 参数
  - 在 AccountBulkUpdate 中添加 schedulable 字段支持
  - 更新 repository 层批量更新 SQL 逻辑
- 前端：在账号管理页面添加批量调度控制
  - 新增"批量启用调度"和"批量停止调度"按钮
  - 添加 handleBulkToggleSchedulable 处理函数
  - 显示具体的成功提示信息（包含操作账号数量）
- 国际化：添加批量调度相关中英文翻译
- 优化：添加 search 参数标准化和验证（account_handler）

frontend/src/views/admin/AccountsView.vue

@@ -19,7 +19,7 @@
         </div>
       </template>
       <template #table>
-        <AccountBulkActionsBar :selected-ids="selIds" @delete="handleBulkDelete" @edit="showBulkEdit = true" @clear="selIds = []" @select-page="selectPage" />
+        <AccountBulkActionsBar :selected-ids="selIds" @delete="handleBulkDelete" @edit="showBulkEdit = true" @clear="selIds = []" @select-page="selectPage" @toggle-schedulable="handleBulkToggleSchedulable" />
         <DataTable :columns="cols" :data="accounts" :loading="loading">
           <template #cell-select="{ row }">
             <input type="checkbox" :checked="selIds.includes(row.id)" @change="toggleSel(row.id)" class="rounded border-gray-300 text-primary-600 focus:ring-primary-500" />
@@ -209,6 +209,21 @@ const openMenu = (a: Account, e: MouseEvent) => { menu.acc = a; menu.pos = { top
 const toggleSel = (id: number) => { const i = selIds.value.indexOf(id); if(i === -1) selIds.value.push(id); else selIds.value.splice(i, 1) }
 const selectPage = () => { selIds.value = [...new Set([...selIds.value, ...accounts.value.map(a => a.id)])] }
 const handleBulkDelete = async () => { if(!confirm(t('common.confirm'))) return; try { await Promise.all(selIds.value.map(id => adminAPI.accounts.delete(id))); selIds.value = []; reload() } catch (error) { console.error('Failed to bulk delete accounts:', error) } }
+const handleBulkToggleSchedulable = async (schedulable: boolean) => {
+  const count = selIds.value.length
+  try {
+    const result = await adminAPI.accounts.bulkUpdate(selIds.value, { schedulable });
+    const message = schedulable
+      ? t('admin.accounts.bulkSchedulableEnabled', { count: result.success || count })
+      : t('admin.accounts.bulkSchedulableDisabled', { count: result.success || count });
+    appStore.showSuccess(message);
+    selIds.value = [];
+    reload()
+  } catch (error) {
+    console.error('Failed to bulk toggle schedulable:', error);
+    appStore.showError(t('common.error'))
+  }
+}
 const handleBulkUpdated = () => { showBulkEdit.value = false; selIds.value = []; reload() }
 const closeTestModal = () => { showTest.value = false; testingAcc.value = null }
 const closeStatsModal = () => { showStats.value = false; statsAcc.value = null }