Remove Programs tab and all supporting code

The Programs feature is superseded by Shows, which provides a more
flexible model with schedule slots. This commit removes all Programs
code across frontend and backend:

Frontend:
- Delete admin-program-form component (ts/html/scss)
- Delete program.service.ts and program.ts interface
- Remove Programs tab, form modal, and all CRUD logic from admin
  component (ts + html)

Backend:
- Delete programs API router
- Remove Program ORM model and ProgramCreate/Update/Response schemas
- Remove programs router registration from main.py
- Remove Program from seed data, seed helpers, and truncate/reset

backend/app/api/admin.py

@@ -2,7 +2,7 @@ from fastapi import APIRouter
 
 from app.config import settings
 from app.database import get_session
-from app.models import DonationTier, Event, Program, StationConfig, Show, ShowSchedule
+from app.models import DonationTier, Event, StationConfig, Show, ShowSchedule
 
 router = APIRouter()
 
@@ -19,7 +19,6 @@ async def reset_database():
     async with async_session() as session:
         await session.execute(ShowSchedule.__table__.delete())
         await session.execute(Show.__table__.delete())
-        await session.execute(Program.__table__.delete())
         await session.execute(Event.__table__.delete())
         await session.execute(DonationTier.__table__.delete())
         await session.execute(StationConfig.__table__.delete())