chore(leaderboard): 用户排行榜当天快照刷新间隔默认调整为半天

ADMIN_LEADERBOARD_TODAY_TTL_SECONDS 默认值 300s -> 43200s，
当天数据约每半天重算一次；调度器 tick、凌晨定稿与手动“刷新当天”不变。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

offline-backend-20260512/backend/CLAUDE.md

@@ -256,7 +256,7 @@ Proxied through nginx: `/api/langgraph/*` → LangGraph, all other `/api/*` →
 
 ### Admin Leaderboard Snapshots (`/api/admin/users/leaderboard*`)
 
-The admin 用户排行榜 is served from **precomputed per-day snapshots** in `admin_leaderboard_daily_stats` (keyed by `(stat_date, settings_hash)`), not by aggregating raw rows on every request. A background scheduler inside the Gateway (`_leaderboard_snapshot_scheduler_loop` in `app/gateway/app.py`, singleton file-locked) ticks every `ADMIN_LEADERBOARD_BACKGROUND_INTERVAL_SECONDS` (default 300s): it prewarms recent days, then builds any `queued`/`error`/stale-`running` day. `GET /leaderboard` merges the per-day snapshots for the requested range. **Today** is rebuilt whenever its snapshot is older than `ADMIN_LEADERBOARD_TODAY_TTL_SECONDS` (default 300s); a past day, once `ready`, is treated as fresh forever.
+The admin 用户排行榜 is served from **precomputed per-day snapshots** in `admin_leaderboard_daily_stats` (keyed by `(stat_date, settings_hash)`), not by aggregating raw rows on every request. A background scheduler inside the Gateway (`_leaderboard_snapshot_scheduler_loop` in `app/gateway/app.py`, singleton file-locked) ticks every `ADMIN_LEADERBOARD_BACKGROUND_INTERVAL_SECONDS` (default 300s): it prewarms recent days, then builds any `queued`/`error`/stale-`running` day. `GET /leaderboard` merges the per-day snapshots for the requested range. **Today** is rebuilt whenever its snapshot is older than `ADMIN_LEADERBOARD_TODAY_TTL_SECONDS` (default 43200s = half a day, so the leaderboard refreshes ~twice daily); a past day, once `ready`, is treated as fresh forever.
 
 Two on-demand/automatic refresh paths layer on top:
 - **Manual "刷新当天"** — `POST /leaderboard/refresh-today` force-rebuilds *today's* snapshot **synchronously** (bounded by the same semaphore/timeout the scheduler uses), then returns the merged range. Lets an admin pull the latest real-time records into the stats without waiting for the TTL. Frontend: a "刷新当天" button on `AdminUserLeaderboardPage` → `useRefreshTodayLeaderboard` (`core/admin/hooks.ts`), which primes + invalidates the `["admin-activity","leaderboard"]` query.

offline-backend-20260512/backend/app/gateway/routers/admin_users.py

@@ -82,7 +82,7 @@ _LEADERBOARD_DAILY_SNAPSHOT_LIMIT = max(
 )
 _LEADERBOARD_TODAY_TTL_SECONDS = max(
     30.0,
-    float(os.getenv("ADMIN_LEADERBOARD_TODAY_TTL_SECONDS", "300")),
+    float(os.getenv("ADMIN_LEADERBOARD_TODAY_TTL_SECONDS", "43200")),
 )
 _LEADERBOARD_QUERY_TIMEOUT_MS = max(
     500,