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/slots/routes.py

@@ -5,8 +5,8 @@ from quart import (
 )
 
 from sqlalchemy.exc import IntegrityError
-from suma_browser.app.authz import require_admin
-from suma_browser.app.redis_cacher import clear_cache
+from shared.browser.app.authz import require_admin
+from shared.browser.app.redis_cacher import clear_cache
 
 from .services.slots import (
   list_slots as svc_list_slots,
@@ -15,11 +15,11 @@ from .services.slots import (
 
 from ..slot.routes import register as register_slot
 
-from suma_browser.app.utils import (
+from shared.browser.app.utils import (
     parse_time,
     parse_cost
 )
-from suma_browser.app.utils.htmx import is_htmx_request
+from shared.browser.app.utils.htmx import is_htmx_request
 
 
 def register():

bp/slots/services/slots.py

@@ -8,6 +8,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from models.calendars import CalendarSlot
 
+
 class SlotError(ValueError):
     pass