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/ticket_type/routes.py

@@ -4,8 +4,8 @@ from quart import (
     request, render_template, make_response, Blueprint, g, jsonify
 )
 
-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.ticket import (
     get_ticket_type as svc_get_ticket_type,
@@ -16,7 +16,7 @@ from .services.ticket import (
 from ..ticket_types.services.tickets import (
     list_ticket_types as svc_list_ticket_types,
 )
-from suma_browser.app.utils.htmx import is_htmx_request
+from shared.browser.app.utils.htmx import is_htmx_request
 
 
 def register():

bp/ticket_type/services/ticket.py

@@ -4,6 +4,7 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from models.calendars import TicketType
+
 from datetime import datetime, timezone