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/slot/routes.py

@@ -6,8 +6,8 @@ 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.slot import (
   update_slot as svc_update_slot,
@@ -19,11 +19,11 @@ from ..slots.services.slots import (
   list_slots as svc_list_slots,
 )
 
-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/slot/services/slot.py

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