refactor: remove deprecated menu_registry.py in favor of module-driven menus

- Delete app/config/menu_registry.py (centralized menu definitions)
- Update app/config/__init__.py to remove menu_registry exports
- Migrate menu_service.py to use menu_discovery_service exclusively
- Add helper methods to menu_discovery_service.py:
  - get_all_menu_item_ids() - get all item IDs for a frontend type
  - get_menu_item() - get specific menu item by ID
  - is_super_admin_only_item() - check if item is super-admin only
  - get_menu_item_module() - get module code for a menu item

Menu items are now defined in each module's definition.py file and
aggregated by MenuDiscoveryService at runtime, enabling true
module-driven architecture.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/config/__init__.py

@@ -1,18 +1,8 @@
 # app/config/__init__.py
 """Configuration modules for the application."""
 
-from .menu_registry import (
-    ADMIN_MENU_REGISTRY,
-    VENDOR_MENU_REGISTRY,
-    AdminMenuItem,
-    VendorMenuItem,
-    get_all_menu_item_ids,
-)
+# Note: menu_registry.py has been deprecated in favor of module-driven menus.
+# Menu items are now defined in each module's definition.py file and aggregated
+# by MenuDiscoveryService (app/modules/core/services/menu_discovery_service.py).
 
-__all__ = [
-    "ADMIN_MENU_REGISTRY",
-    "VENDOR_MENU_REGISTRY",
-    "AdminMenuItem",
-    "VendorMenuItem",
-    "get_all_menu_item_ids",
-]
+__all__ = []