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/markets/routes.py

@@ -5,16 +5,16 @@ from quart import (
 )
 from sqlalchemy import select
 
-from models.market_place import MarketPlace
+from market.models.market_place import MarketPlace
 
 from .services.markets import (
     create_market as svc_create_market,
     soft_delete as svc_soft_delete,
 )
 
-from suma_browser.app.redis_cacher import cache_page, clear_cache
-from suma_browser.app.authz import require_admin
-from suma_browser.app.utils.htmx import is_htmx_request
+from shared.browser.app.redis_cacher import cache_page, clear_cache
+from shared.browser.app.authz import require_admin
+from shared.browser.app.utils.htmx import is_htmx_request
 
 
 def register():