refactor: complete module-driven architecture migration

This commit completes the migration to a fully module-driven architecture:

## Models Migration
- Moved all domain models from models/database/ to their respective modules:
  - tenancy: User, Admin, Vendor, Company, Platform, VendorDomain, etc.
  - cms: MediaFile, VendorTheme
  - messaging: Email, VendorEmailSettings, VendorEmailTemplate
  - core: AdminMenuConfig
- models/database/ now only contains Base and TimestampMixin (infrastructure)

## Schemas Migration
- Moved all domain schemas from models/schema/ to their respective modules:
  - tenancy: company, vendor, admin, team, vendor_domain
  - cms: media, image, vendor_theme
  - messaging: email
- models/schema/ now only contains base.py and auth.py (infrastructure)

## Routes Migration
- Moved admin routes from app/api/v1/admin/ to modules:
  - menu_config.py -> core module
  - modules.py -> tenancy module
  - module_config.py -> tenancy module
- app/api/v1/admin/ now only aggregates auto-discovered module routes

## Menu System
- Implemented module-driven menu system with MenuDiscoveryService
- Extended FrontendType enum: PLATFORM, ADMIN, VENDOR, STOREFRONT
- Added MenuItemDefinition and MenuSectionDefinition dataclasses
- Each module now defines its own menu items in definition.py
- MenuService integrates with MenuDiscoveryService for template rendering

## Documentation
- Updated docs/architecture/models-structure.md
- Updated docs/architecture/menu-management.md
- Updated architecture validation rules for new exceptions

## Architecture Validation
- Updated MOD-019 rule to allow base.py in models/schema/
- Created core module exceptions.py and schemas/ directory
- All validation errors resolved (only warnings remain)

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

app/modules/cms/services/media_service.py

@@ -27,7 +27,7 @@ from app.modules.cms.exceptions import (
     UnsupportedMediaTypeException,
     MediaFileTooLargeException,
 )
-from models.database.media import MediaFile
+from app.modules.cms.models import MediaFile
 from app.modules.catalog.models import ProductMedia
 
 logger = logging.getLogger(__name__)

app/modules/cms/services/vendor_email_settings_service.py

@@ -24,14 +24,13 @@ from app.exceptions import (
     ValidationException,
     ExternalServiceException,
 )
-from models.database import (
-    Vendor,
+from app.modules.tenancy.models import Vendor
+from app.modules.messaging.models import (
     VendorEmailSettings,
     EmailProvider,
     PREMIUM_EMAIL_PROVIDERS,
-    VendorSubscription,
-    TierCode,
 )
+from app.modules.billing.models import VendorSubscription, TierCode
 
 logger = logging.getLogger(__name__)
 

app/modules/cms/services/vendor_theme_service.py

@@ -26,9 +26,9 @@ from app.modules.cms.exceptions import (
     ThemeValidationException,
     VendorThemeNotFoundException,
 )
-from models.database.vendor import Vendor
-from models.database.vendor_theme import VendorTheme
-from models.schema.vendor_theme import ThemePresetPreview, VendorThemeUpdate
+from app.modules.tenancy.models import Vendor
+from app.modules.cms.models import VendorTheme
+from app.modules.cms.schemas.vendor_theme import ThemePresetPreview, VendorThemeUpdate
 
 logger = logging.getLogger(__name__)