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>

tests/unit/services/test_admin_service.py

@@ -12,7 +12,7 @@ from app.modules.tenancy.exceptions import (
 )
 from app.modules.tenancy.services.admin_service import AdminService
 from app.modules.analytics.services.stats_service import stats_service
-from models.schema.vendor import VendorCreate
+from app.modules.tenancy.schemas.vendor import VendorCreate
 
 
 @pytest.mark.unit
@@ -56,7 +56,7 @@ class TestAdminService:
 
     def test_toggle_user_status_activate(self, db, test_user, test_admin):
         """Test activating a user"""
-        from models.database.user import User
+        from app.modules.tenancy.models import User
 
         # Re-query user to get fresh instance
         user_to_deactivate = db.query(User).filter(User.id == test_user.id).first()
@@ -122,7 +122,7 @@ class TestAdminService:
 
     def test_verify_vendor_mark_verified(self, db, test_vendor):
         """Test marking vendor as verified"""
-        from models.database.vendor import Vendor
+        from app.modules.tenancy.models import Vendor
 
         # Re-query vendor to get fresh instance
         vendor_to_unverify = (
@@ -373,7 +373,7 @@ class TestAdminServiceVendorCreation:
         assert vendor.vendor_code == vendor_data.vendor_code.upper()
 
         # Verify platform assignment
-        from models.database.vendor_platform import VendorPlatform
+        from app.modules.tenancy.models import VendorPlatform
 
         assignment = (
             db.query(VendorPlatform)
@@ -408,7 +408,7 @@ class TestAdminServiceVendorCreation:
         assert vendor is not None
 
         # Verify both platform assignments
-        from models.database.vendor_platform import VendorPlatform
+        from app.modules.tenancy.models import VendorPlatform
 
         assignments = (
             db.query(VendorPlatform)
@@ -442,7 +442,7 @@ class TestAdminServiceVendorCreation:
         assert vendor is not None
 
         # Verify no platform assignments created
-        from models.database.vendor_platform import VendorPlatform
+        from app.modules.tenancy.models import VendorPlatform
 
         assignments = (
             db.query(VendorPlatform)