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/billing/definition.py

@@ -6,8 +6,8 @@ Defines the billing module including its features, menu items,
 route configurations, and scheduled tasks.
 """
 
-from app.modules.base import ModuleDefinition, ScheduledTask
-from models.database.admin_menu_config import FrontendType
+from app.modules.base import MenuItemDefinition, MenuSectionDefinition, ModuleDefinition, ScheduledTask
+from app.modules.enums import FrontendType
 
 
 def _get_admin_router():
@@ -53,6 +53,72 @@ billing_module = ModuleDefinition(
             "invoices",  # Vendor invoice history
         ],
     },
+    # New module-driven menu definitions
+    menus={
+        FrontendType.ADMIN: [
+            MenuSectionDefinition(
+                id="billing",
+                label_key="billing.menu.billing_subscriptions",
+                icon="credit-card",
+                order=50,
+                items=[
+                    MenuItemDefinition(
+                        id="subscription-tiers",
+                        label_key="billing.menu.subscription_tiers",
+                        icon="tag",
+                        route="/admin/subscription-tiers",
+                        order=10,
+                    ),
+                    MenuItemDefinition(
+                        id="subscriptions",
+                        label_key="billing.menu.vendor_subscriptions",
+                        icon="credit-card",
+                        route="/admin/subscriptions",
+                        order=20,
+                    ),
+                    MenuItemDefinition(
+                        id="billing-history",
+                        label_key="billing.menu.billing_history",
+                        icon="document-text",
+                        route="/admin/billing-history",
+                        order=30,
+                    ),
+                ],
+            ),
+        ],
+        FrontendType.VENDOR: [
+            MenuSectionDefinition(
+                id="sales",
+                label_key="billing.menu.sales_orders",
+                icon="currency-euro",
+                order=20,
+                items=[
+                    MenuItemDefinition(
+                        id="invoices",
+                        label_key="billing.menu.invoices",
+                        icon="currency-euro",
+                        route="/vendor/{vendor_code}/invoices",
+                        order=30,
+                    ),
+                ],
+            ),
+            MenuSectionDefinition(
+                id="account",
+                label_key="billing.menu.account_settings",
+                icon="credit-card",
+                order=900,
+                items=[
+                    MenuItemDefinition(
+                        id="billing",
+                        label_key="billing.menu.billing",
+                        icon="credit-card",
+                        route="/vendor/{vendor_code}/billing",
+                        order=30,
+                    ),
+                ],
+            ),
+        ],
+    },
     is_core=False,  # Billing can be disabled (e.g., internal platforms)
     # =========================================================================
     # Self-Contained Module Configuration