feat(dashboard): add admin user analytics and fix chart labels

- Add GET /api/data/users endpoint for user-grouped quota data (admin only)
- Add user consumption ranking (horizontal bar, top 10) and user consumption
  trend (area chart) tabs visible only to admin users
- Fix mislabeled "消耗趋势" tab to "调用趋势" (shows call counts, not quota)
- Add processUserData helper for user ranking and trend data extraction
- Add i18n keys for new tabs across all 7 locales

web/src/i18n/locales/ja.json

@@ -3020,6 +3020,10 @@
     "调用次数": "呼び出し回数",
     "调用次数分布": "呼び出し回数分布",
     "调用次数排行": "呼び出し回数ランキング",
+    "调用趋势": "呼び出し推移",
+    "模型排行": "モデルランキング",
+    "用户消耗排行": "ユーザー消費ランキング",
+    "用户消耗趋势": "ユーザー消費推移",
     "调试信息": "デバッグ情報",
     "谨慎": "注意",
     "豆包": "豆包",