feat(frontend): 前端界面优化与使用统计功能增强 (#46)

* feat(frontend): 前端界面优化与使用统计功能增强

主要改动:

1. 表格布局统一优化
   - 新增 TablePageLayout 通用布局组件
   - 统一所有管理页面的表格样式和交互
   - 优化 DataTable、Pagination、Select 等通用组件

2. 使用统计功能增强
   - 管理端: 添加完整的筛选和显示功能
   - 用户端: 完善 API Key 列显示
   - 后端: 优化使用统计数据结构和查询

3. 账户组件优化
   - 优化 AccountStatsModal、AccountUsageCell 等组件
   - 统一进度条和统计显示样式

4. 其他改进
   - 完善中英文国际化
   - 统一页面样式和交互体验
   - 优化各视图页面的响应式布局

* fix(test): 修复 stubUsageLogRepo.ListWithFilters 测试 stub

测试用例 GET /api/v1/usage 返回 500 是因为 stub 方法未实现，
现在正确返回基于 UserID 过滤的日志数据。

* feat(frontend): 统一日期时间显示格式

**主要改动**:
1. 增强 utils/format.ts:
   - 新增 formatDateOnly() - 格式: YYYY-MM-DD
   - 新增 formatDateTime() - 格式: YYYY-MM-DD HH:mm:ss

2. 全局替换视图中的格式化函数:
   - 移除各视图中的自定义 formatDate 函数
   - 统一导入使用 @/utils/format 中的函数
   - created_at/updated_at 使用 formatDateTime
   - expires_at 使用 formatDateOnly

3. 受影响的视图 (8个):
   - frontend/src/views/user/KeysView.vue
   - frontend/src/views/user/DashboardView.vue
   - frontend/src/views/user/UsageView.vue
   - frontend/src/views/user/RedeemView.vue
   - frontend/src/views/admin/UsersView.vue
   - frontend/src/views/admin/UsageView.vue
   - frontend/src/views/admin/RedeemView.vue
   - frontend/src/views/admin/SubscriptionsView.vue

**效果**:
- 日期统一显示为 YYYY-MM-DD
- 时间统一显示为 YYYY-MM-DD HH:mm:ss
- 提升可维护性，避免格式不一致

* fix(frontend): 补充遗漏的时间格式化统一

**补充修复**（基于 code review 发现的遗漏）:

1. 增强 utils/format.ts:
   - 新增 formatTime() - 格式: HH:mm

2. 修复 4 个遗漏的文件:
   - src/views/admin/UsersView.vue
     * 删除 formatExpiresAt()，改用 formatDateTime()
     * 修复订阅过期时间 tooltip 显示格式不一致问题

   - src/views/user/ProfileView.vue
     * 删除 formatMemberSince()，改用 formatDate(date, 'YYYY-MM')
     * 统一会员起始时间显示格式

   - src/views/user/SubscriptionsView.vue
     * 修改 formatExpirationDate() 使用 formatDateOnly()
     * 保留天数计算逻辑

   - src/components/account/AccountStatusIndicator.vue
     * 删除本地 formatTime()，改用 utils/format 中的统一函数
     * 修复 rate limit 和 overload 重置时间显示

**验证**:
- TypeScript 类型检查通过 ✓
- 前端构建成功 ✓
- 所有剩余的 toLocaleString() 都是数字格式化，属于正确用法 ✓

**效果**:
- 订阅过期时间统一为 YYYY-MM-DD HH:mm:ss
- 会员起始时间统一为 YYYY-MM
- 重置时间统一为 HH:mm
- 消除所有不规范的原生 locale 方法调用

frontend/src/views/user/RedeemView.vue

@@ -377,7 +377,7 @@
                     {{ getHistoryItemTitle(item) }}
                   </p>
                   <p class="text-xs text-gray-500 dark:text-dark-400">
-                    {{ formatDate(item.used_at) }}
+                    {{ formatDateTime(item.used_at) }}
                   </p>
                 </div>
               </div>
@@ -447,6 +447,7 @@ import { useAuthStore } from '@/stores/auth'
 import { useAppStore } from '@/stores/app'
 import { redeemAPI, authAPI, type RedeemHistoryItem } from '@/api'
 import AppLayout from '@/components/layout/AppLayout.vue'
+import { formatDateTime } from '@/utils/format'
 
 const { t } = useI18n()
 const authStore = useAuthStore()
@@ -472,18 +473,6 @@ const history = ref<RedeemHistoryItem[]>([])
 const loadingHistory = ref(false)
 const contactInfo = ref('')
 
-const formatDate = (dateString: string) => {
-  if (!dateString) return '-'
-  const date = new Date(dateString)
-  return date.toLocaleDateString('en-US', {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric',
-    hour: '2-digit',
-    minute: '2-digit'
-  })
-}
-
 // Helper functions for history display
 const isBalanceType = (type: string) => {
   return type === 'balance' || type === 'admin_balance'

frontend/src/views/user/SubscriptionsView.vue

@@ -257,6 +257,7 @@ import { useAppStore } from '@/stores/app'
 import subscriptionsAPI from '@/api/subscriptions'
 import type { UserSubscription } from '@/types'
 import AppLayout from '@/components/layout/AppLayout.vue'
+import { formatDateOnly } from '@/utils/format'
 
 const { t } = useI18n()
 const appStore = useAppStore()
@@ -300,11 +301,7 @@ function formatExpirationDate(expiresAt: string): string {
     return t('userSubscriptions.status.expired')
   }
 
-  const dateStr = expires.toLocaleDateString(undefined, {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric'
-  })
+  const dateStr = formatDateOnly(expires)
 
   if (days === 0) {
     return `${dateStr} (Today)`

frontend/src/views/user/UsageView.vue

 <template>
   <AppLayout>
-    <div class="space-y-6">
-      <!-- Summary Stats Cards -->
-      <div class="grid grid-cols-2 gap-4 lg:grid-cols-4">
-        <!-- Total Requests -->
-        <div class="card p-4">
+    <TablePageLayout>
+      <template #actions>
+        <div class="grid grid-cols-2 gap-4 lg:grid-cols-4">
+          <!-- Total Requests -->
+          <div class="card p-4">
           <div class="flex items-center gap-3">
             <div class="rounded-lg bg-blue-100 p-2 dark:bg-blue-900/30">
               <svg
@@ -131,11 +131,12 @@
             </div>
           </div>
         </div>
-      </div>
+        </div>
+      </template>
 
-      <!-- Filters -->
-      <div class="card">
-        <div class="px-6 py-4">
+      <template #filters>
+        <div class="card">
+          <div class="px-6 py-4">
           <div class="flex flex-wrap items-end gap-4">
             <!-- API Key Filter -->
             <div class="min-w-[180px]">
@@ -169,11 +170,17 @@
             </div>
           </div>
         </div>
-      </div>
+        </div>
+      </template>
 
-      <!-- Usage Table -->
-      <div class="card overflow-hidden">
+      <template #table>
         <DataTable :columns="columns" :data="usageLogs" :loading="loading">
+          <template #cell-api_key="{ row }">
+            <span class="text-sm text-gray-900 dark:text-white">{{
+              row.api_key?.name || '-'
+            }}</span>
+          </template>
+
           <template #cell-model="{ value }">
             <span class="font-medium text-gray-900 dark:text-white">{{ value }}</span>
           </template>
@@ -379,17 +386,18 @@
             <EmptyState :message="t('usage.noRecords')" />
           </template>
         </DataTable>
-      </div>
-
-      <!-- Pagination -->
-      <Pagination
-        v-if="pagination.total > 0"
-        :page="pagination.page"
-        :total="pagination.total"
-        :page-size="pagination.page_size"
-        @update:page="handlePageChange"
-      />
-    </div>
+      </template>
+
+      <template #pagination>
+        <Pagination
+          v-if="pagination.total > 0"
+          :page="pagination.page"
+          :total="pagination.total"
+          :page-size="pagination.page_size"
+          @update:page="handlePageChange"
+        />
+      </template>
+    </TablePageLayout>
   </AppLayout>
 </template>
 
@@ -399,6 +407,7 @@ import { useI18n } from 'vue-i18n'
 import { useAppStore } from '@/stores/app'
 import { usageAPI, keysAPI } from '@/api'
 import AppLayout from '@/components/layout/AppLayout.vue'
+import TablePageLayout from '@/components/layout/TablePageLayout.vue'
 import DataTable from '@/components/common/DataTable.vue'
 import Pagination from '@/components/common/Pagination.vue'
 import EmptyState from '@/components/common/EmptyState.vue'
@@ -406,6 +415,7 @@ import Select from '@/components/common/Select.vue'
 import DateRangePicker from '@/components/common/DateRangePicker.vue'
 import type { UsageLog, ApiKey, UsageQueryParams, UsageStatsResponse } from '@/types'
 import type { Column } from '@/components/common/types'
+import { formatDateTime } from '@/utils/format'
 
 const { t } = useI18n()
 const appStore = useAppStore()
@@ -414,6 +424,7 @@ const appStore = useAppStore()
 const usageStats = ref<UsageStatsResponse | null>(null)
 
 const columns = computed<Column[]>(() => [
+  { key: 'api_key', label: t('usage.apiKeyFilter'), sortable: false },
   { key: 'model', label: t('usage.model'), sortable: true },
   { key: 'stream', label: t('usage.type'), sortable: false },
   { key: 'tokens', label: t('usage.tokens'), sortable: false },
@@ -505,17 +516,6 @@ const formatCacheTokens = (value: number): string => {
   return value.toLocaleString()
 }
 
-const formatDateTime = (dateString: string): string => {
-  const date = new Date(dateString)
-  return date.toLocaleString('en-US', {
-    year: 'numeric',
-    month: 'short',
-    day: 'numeric',
-    hour: '2-digit',
-    minute: '2-digit'
-  })
-}
-
 const loadUsageLogs = async () => {
   loading.value = true
   try {