Add time-based day progress bar to dashboards

Replaces block-count progress with a wall-clock progress bar driven by
configurable day start/end hours on each schedule template.

- ScheduleTemplate: add day_start_time / day_end_time (TIME, nullable)
- Startup migration: idempotent ALTER TABLE for existing DBs
- Dashboard snapshot: includes day_start_time / day_end_time from template
- Admin → Schedules: time pickers in block editor to set day hours
- Dashboard view: time-based progress bar with start/current/end labels
- TV view: full-width day progress strip between header and main content

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/routers/dashboard.py

@@ -11,7 +11,7 @@ from sqlalchemy.orm import selectinload
 
 from app.dependencies import get_db
 from app.models.child import Child
-from app.models.schedule import ScheduleBlock
+from app.models.schedule import ScheduleBlock, ScheduleTemplate
 from app.models.session import DailySession, TimerEvent
 from app.schemas.session import DashboardSnapshot
 
@@ -41,6 +41,8 @@ async def get_dashboard(child_id: int, db: AsyncSession = Depends(get_db)):
     blocks = []
     completed_ids = []
     block_elapsed_seconds = 0
+    day_start_time = None
+    day_end_time = None
 
     if session and session.template_id:
         blocks_result = await db.execute(
@@ -50,6 +52,14 @@ async def get_dashboard(child_id: int, db: AsyncSession = Depends(get_db)):
         )
         blocks = blocks_result.scalars().all()
 
+        template_result = await db.execute(
+            select(ScheduleTemplate).where(ScheduleTemplate.id == session.template_id)
+        )
+        template = template_result.scalar_one_or_none()
+        if template:
+            day_start_time = template.day_start_time
+            day_end_time = template.day_end_time
+
         events_result = await db.execute(
             select(TimerEvent).where(
                 TimerEvent.session_id == session.id,
@@ -88,4 +98,6 @@ async def get_dashboard(child_id: int, db: AsyncSession = Depends(get_db)):
         blocks=blocks,
         completed_block_ids=completed_ids,
         block_elapsed_seconds=block_elapsed_seconds,
+        day_start_time=day_start_time,
+        day_end_time=day_end_time,
     )