feat(ops): 运维监控新增 OpenAI Token 请求统计表

- 新增管理端接口 /api/v1/admin/ops/dashboard/openai-token-stats，按模型聚合统计 gpt% 请求

- 支持 time_range=30m|1h|1d|15d|30d（默认 30d），支持 platform/group_id 过滤

- 支持分页（page/page_size）或 TopN（top_n）互斥查询

- 前端运维监控页新增统计表卡片，包含空态/错误态与分页/TopN 交互

- 补齐后端与前端测试

frontend/src/views/admin/ops/OpsDashboard.vue

@@ -84,6 +84,15 @@
         />
       </div>
 
+      <!-- Row: OpenAI Token Stats -->
+      <div v-if="opsEnabled && !(loading && !hasLoadedOnce)" class="grid grid-cols-1 gap-6">
+        <OpsOpenAITokenStatsCard
+          :platform-filter="platform"
+          :group-id-filter="groupId"
+          :refresh-token="dashboardRefreshToken"
+        />
+      </div>
+
       <!-- Alert Events -->
       <OpsAlertEventsCard v-if="opsEnabled && !(loading && !hasLoadedOnce)" />
 
@@ -148,6 +157,7 @@ import OpsLatencyChart from './components/OpsLatencyChart.vue'
 import OpsThroughputTrendChart from './components/OpsThroughputTrendChart.vue'
 import OpsSwitchRateTrendChart from './components/OpsSwitchRateTrendChart.vue'
 import OpsAlertEventsCard from './components/OpsAlertEventsCard.vue'
+import OpsOpenAITokenStatsCard from './components/OpsOpenAITokenStatsCard.vue'
 import OpsRequestDetailsModal, { type OpsRequestDetailsPreset } from './components/OpsRequestDetailsModal.vue'
 import OpsSettingsDialog from './components/OpsSettingsDialog.vue'
 import OpsAlertRulesCard from './components/OpsAlertRulesCard.vue'