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/dashboard.py

@@ -13,7 +13,7 @@ from app.dependencies import get_db
 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.schemas.session import DashboardSnapshot
@@ -45,8 +45,6 @@ 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(
@@ -57,14 +55,6 @@ 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,
@@ -101,8 +91,6 @@ async def get_dashboard(child_id: int, db: AsyncSession = Depends(get_db)):
         completed_block_ids=completed_ids,
         block_elapsed_seconds=block_elapsed_seconds,
         is_paused=is_paused,
-        day_start_time=day_start_time,
-        day_end_time=day_end_time,
         morning_routine=morning_routine,
         break_activities=break_activities,
     )