Import all app model packages at startup for SQLAlchemy mapper

Cross-domain relationships like Product.order_items → OrderItem use
string references that SQLAlchemy resolves by class name lookup. All
model packages must be imported so every class is registered before
mapper configuration runs.

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

infrastructure/factory.py

@@ -8,7 +8,14 @@ from typing import Callable, Awaitable, Sequence
 from quart import Quart, request, g, send_from_directory
 
 from shared.config import init_config, config, pretty
-from shared.models import KV  # ensure models imported
+from shared.models import KV  # ensure shared models imported
+# Register all app model classes with SQLAlchemy so cross-domain
+# relationship() string references resolve correctly.
+for _mod in ("blog.models", "market.models", "cart.models", "events.models"):
+    try:
+        __import__(_mod)
+    except ImportError:
+        pass
 from shared.log_config import configure_logging
 from shared.events import EventProcessor