Add 8-hour default window for legacy-meter deploy monitoring

Expose hours query param on /legacy-meter/summary and weekly-review;
capture_legacy_meter_evidence.py defaults to --hours 8 (--days 7 for
weekly retirement gate). Re-capture post-deploy evidence with tighter window.

api/routers/legacy_meter.py

@@ -28,6 +28,21 @@ from api.services.legacy_meter import (
 router = APIRouter(prefix="/legacy-meter", tags=["legacy-meter"])
 
 
+def _review_window(
+    *,
+    days: int | None,
+    hours: int | None,
+    window_start: datetime | None,
+    window_end: datetime | None,
+) -> tuple[datetime, datetime]:
+    end = window_end or datetime.now(tz=timezone.utc)
+    if window_start is not None:
+        return window_start, end
+    if hours is not None:
+        return end - timedelta(hours=hours), end
+    return end - timedelta(days=days or 7), end
+
+
 @router.post(
     "/interfaces",
     response_model=LegacyInterfaceRead,
@@ -107,23 +122,43 @@ async def record_usage(
 
 @router.get("/summary", response_model=LegacyUsageSummary)
 async def usage_summary(
-    days: int = Query(7, ge=1, le=366),
+    days: int | None = Query(None, ge=1, le=366),
+    hours: int | None = Query(None, ge=1, le=8784),
     window_start: datetime | None = None,
     window_end: datetime | None = None,
     session: AsyncSession = Depends(get_session),
 ) -> LegacyUsageSummary:
-    end = window_end or datetime.now(tz=timezone.utc)
-    start = window_start or (end - timedelta(days=days))
+    if days is not None and hours is not None:
+        raise HTTPException(
+            status_code=422,
+            detail="Pass either days or hours, not both",
+        )
+    start, end = _review_window(
+        days=days,
+        hours=hours,
+        window_start=window_start,
+        window_end=window_end,
+    )
     return await legacy_usage_summary(session, window_start=start, window_end=end)
 
 
 @router.get("/weekly-review", response_model=LegacyWeeklyReview)
 async def weekly_review(
-    days: int = Query(7, ge=1, le=366),
+    days: int | None = Query(None, ge=1, le=366),
+    hours: int | None = Query(None, ge=1, le=8784),
     window_start: datetime | None = None,
     window_end: datetime | None = None,
     session: AsyncSession = Depends(get_session),
 ) -> LegacyWeeklyReview:
-    end = window_end or datetime.now(tz=timezone.utc)
-    start = window_start or (end - timedelta(days=days))
+    if days is not None and hours is not None:
+        raise HTTPException(
+            status_code=422,
+            detail="Pass either days or hours, not both",
+        )
+    start, end = _review_window(
+        days=days,
+        hours=hours,
+        window_start=window_start,
+        window_end=window_end,
+    )
     return await legacy_weekly_review(session, window_start=start, window_end=end)