feat: complete frozen MVP — period-aware stats, layout-driven UI, quick checkin

- Fix first daily record 422 (expectedVersion now accepts 0)
- Add period_window + summarize; /api/summary and /api/tasks/{id}/summary
  aggregate each metric inside its own day/week/month/lifetime window,
  reading raw facts only (never the rebuildable month archives)
- Drive frontend rendering from per-page layout JSON with a component
  registry; scope/cardinality enforced server-side, invalid layouts fall back
- Add quick checkin and duration input in H:M:S that round-trips integer seconds
- Fix heatmap/completedAt timezone drift to Asia/Shanghai
- Add server-side session TTL (30d) matching the login cookie
- Handle date.min/date.max boundaries without OverflowError
- Half-up rounding to match browser Math.round

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/main.py

@@ -198,6 +198,14 @@ def create_app(
     async def upsert_daily(task_id: str, logical_date: date, payload: DailyRecordInput) -> dict:
         return repository.upsert_daily(task_id, logical_date, payload)
 
+    @app.get("/api/summary")
+    async def summary(date_: Annotated[date | None, Query(alias="date")] = None) -> dict:
+        return repository.summarize(date_)
+
+    @app.get("/api/tasks/{task_id}/summary")
+    async def task_summary(task_id: str, date_: Annotated[date | None, Query(alias="date")] = None) -> dict:
+        return repository.summarize(date_, task_id)
+
     @app.get("/api/tasks/{task_id}/history")
     async def history(
         task_id: str,