Remove school day hours from schedule templates

The day progress bar no longer uses day start/end times (it uses block
durations instead), so the field is no longer needed.

Removed from: Admin UI, schedule store, schedule model/schemas/router,
session broadcast payload, dashboard snapshot, and startup migrations.
DB columns are left in place (harmless, no migration required).

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

backend/app/routers/sessions.py

@@ -9,7 +9,7 @@ from app.dependencies import get_db, get_current_user
 from app.models.child import Child
 from app.models.morning_routine import MorningRoutineItem
 from app.models.break_activity import BreakActivityItem
-from app.models.schedule import ScheduleBlock, ScheduleTemplate
+from app.models.schedule import ScheduleBlock
 from app.models.subject import Subject  # noqa: F401 — needed for selectinload chain
 from app.models.session import DailySession, TimerEvent
 from app.models.user import User
@@ -23,8 +23,6 @@ router = APIRouter(prefix="/api/sessions", tags=["sessions"])
 async def _broadcast_session(db: AsyncSession, session: DailySession) -> None:
     """Build a snapshot dict and broadcast it to all connected TVs for this child."""
     blocks = []
-    day_start_time = None
-    day_end_time = None
 
     if session.template_id:
         blocks_result = await db.execute(
@@ -56,14 +54,6 @@ async def _broadcast_session(db: AsyncSession, session: DailySession) -> None:
             for b in 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 = str(template.day_start_time) if template.day_start_time else None
-            day_end_time = str(template.day_end_time) if template.day_end_time else None
-
     # Gather completed block IDs from timer events
     events_result = await db.execute(
         select(TimerEvent).where(
@@ -105,8 +95,6 @@ async def _broadcast_session(db: AsyncSession, session: DailySession) -> None:
         },
         "blocks": blocks,
         "completed_block_ids": completed_ids,
-        "day_start_time": day_start_time,
-        "day_end_time": day_end_time,
         "morning_routine": morning_routine,
         "break_activities": break_activities,
     }