feat: decouple events from shared_lib, add app-owned models

Phase 1-3 of decoupling:
- path_setup.py adds project root to sys.path
- Events-owned models in events/models/ (calendars with all related models)
- All imports updated: shared.infrastructure, shared.db, shared.browser, etc.
- Calendar uses container_type/container_id instead of post_id FK
- CalendarEntryPost uses content_type/content_id (generic content refs)

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

bp/calendar_entry/services/ticket_operations.py

@@ -9,6 +9,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from models.calendars import CalendarEntry
 
 
+
 async def update_ticket_config(
     session: AsyncSession,
     entry_id: int,