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/tenancy/models/__init__.py

@@ -2,13 +2,53 @@
 """
 Tenancy module database models.
 
-Models for platform, company, vendor, and admin user management.
-Currently models remain in models/database/ - this package is a placeholder
-for future migration.
+This is the canonical location for tenancy module models including:
+- Platform, Company, Vendor, User management
+- Admin platform assignments
+- Vendor platform memberships
+- Platform module configuration
+- Vendor domains
 """
 
-# Models will be migrated here from models/database/
-# For now, import from legacy location if needed:
-# from models.database.vendor import Vendor
-# from models.database.company import Company
-# from models.database.platform import Platform
+from app.modules.tenancy.models.admin import (
+    AdminAuditLog,
+    AdminSession,
+    AdminSetting,
+    ApplicationLog,
+    PlatformAlert,
+)
+from app.modules.tenancy.models.admin_platform import AdminPlatform
+from app.modules.tenancy.models.company import Company
+from app.modules.tenancy.models.platform import Platform
+from app.modules.tenancy.models.platform_module import PlatformModule
+from app.modules.tenancy.models.user import User, UserRole
+from app.modules.tenancy.models.vendor import Role, Vendor, VendorUser, VendorUserType
+from app.modules.tenancy.models.vendor_domain import VendorDomain
+from app.modules.tenancy.models.vendor_platform import VendorPlatform
+
+__all__ = [
+    # Admin models
+    "AdminAuditLog",
+    "AdminSession",
+    "AdminSetting",
+    "ApplicationLog",
+    "PlatformAlert",
+    # Admin-Platform junction
+    "AdminPlatform",
+    # Company
+    "Company",
+    # Platform
+    "Platform",
+    "PlatformModule",
+    # User
+    "User",
+    "UserRole",
+    # Vendor
+    "Vendor",
+    "VendorUser",
+    "VendorUserType",
+    "Role",
+    # Vendor configuration
+    "VendorDomain",
+    "VendorPlatform",
+]