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/i18n/locales/en.ts

@@ -2508,11 +2508,33 @@ export default {
         '5m': 'Last 5 minutes',
         '30m': 'Last 30 minutes',
         '1h': 'Last 1 hour',
+        '1d': 'Last 1 day',
+        '15d': 'Last 15 days',
         '6h': 'Last 6 hours',
         '24h': 'Last 24 hours',
         '7d': 'Last 7 days',
         '30d': 'Last 30 days'
       },
+      openaiTokenStats: {
+        title: 'OpenAI Token Request Stats',
+        viewModeTopN: 'TopN',
+        viewModePagination: 'Pagination',
+        prevPage: 'Previous',
+        nextPage: 'Next',
+        pageInfo: 'Page {page}/{total}',
+        totalModels: 'Total models: {total}',
+        failedToLoad: 'Failed to load OpenAI token stats',
+        empty: 'No OpenAI token stats for the current filters',
+        table: {
+          model: 'Model',
+          requestCount: 'Requests',
+          avgTokensPerSec: 'Avg Tokens/sec',
+          avgFirstTokenMs: 'Avg First Token Latency (ms)',
+          totalOutputTokens: 'Total Output Tokens',
+          avgDurationMs: 'Avg Duration (ms)',
+          requestsWithFirstToken: 'Requests With First Token'
+        }
+      },
       fullscreen: {
         enter: 'Enter Fullscreen'
       },