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/models.py

@@ -89,7 +89,7 @@ class MetricValue(BaseModel):
 class DailyRecordInput(BaseModel):
     model_config = ConfigDict(extra="forbid", str_strip_whitespace=True)
 
-    expectedVersion: Annotated[int | None, Field(ge=1)] = None
+    expectedVersion: Annotated[int | None, Field(ge=0)] = None
     note: Annotated[str, Field(max_length=4000)] = ""
     completedAt: datetime | None = None
     values: list[MetricValue] = Field(default_factory=list)