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/core/locales/lb.json

@@ -0,0 +1,71 @@
+{
+  "dashboard": {
+    "title": "Dashboard",
+    "welcome": "Wëllkomm zréck",
+    "overview": "Iwwersiicht",
+    "quick_stats": "Séier Statistiken",
+    "recent_activity": "Rezent Aktivitéit",
+    "total_products": "Produkter insgesamt",
+    "total_orders": "Bestellungen insgesamt",
+    "total_customers": "Clienten insgesamt",
+    "total_revenue": "Ëmsaz insgesamt",
+    "active_products": "Aktiv Produkter",
+    "pending_orders": "Aussteesend Bestellungen",
+    "new_customers": "Nei Clienten",
+    "today": "Haut",
+    "this_week": "Dës Woch",
+    "this_month": "Dëse Mount",
+    "this_year": "Dëst Joer",
+    "error_loading": "Feeler beim Lueden vum Dashboard",
+    "no_data": "Keng Donnéeën disponibel"
+  },
+  "settings": {
+    "title": "Astellungen",
+    "general": "Allgemeng",
+    "store": "Buttek",
+    "store_name": "Butteknumm",
+    "store_description": "Buttekbeschreiwung",
+    "contact_email": "Kontakt E-Mail",
+    "contact_phone": "Kontakt Telefon",
+    "business_address": "Geschäftsadress",
+    "tax_number": "Steiernummer",
+    "currency": "Wärung",
+    "timezone": "Zäitzon",
+    "language": "Sprooch",
+    "language_settings": "Sproochastellungen",
+    "default_language": "Standard Sprooch",
+    "dashboard_language": "Dashboard Sprooch",
+    "storefront_language": "Buttek Sprooch",
+    "enabled_languages": "Aktivéiert Sproochen",
+    "notifications": "Notifikatiounen",
+    "email_notifications": "E-Mail Notifikatiounen",
+    "integrations": "Integratiounen",
+    "api_keys": "API Schlësselen",
+    "webhooks": "Webhooks",
+    "save_settings": "Astellunge späicheren",
+    "settings_saved": "Astellungen erfollegräich gespäichert"
+  },
+  "profile": {
+    "title": "Profil",
+    "my_profile": "Mäi Profil",
+    "edit_profile": "Profil änneren",
+    "personal_info": "Perséinlech Informatiounen",
+    "first_name": "Virnumm",
+    "last_name": "Nonumm",
+    "email": "E-Mail",
+    "phone": "Telefon",
+    "avatar": "Avatar",
+    "change_avatar": "Avatar änneren",
+    "security": "Sécherheet",
+    "two_factor": "Zwee-Faktor Authentifikatioun",
+    "sessions": "Aktiv Sessiounen",
+    "preferences": "Astellungen",
+    "language_preference": "Sproochpräferenz",
+    "save_profile": "Profil späicheren",
+    "profile_updated": "Profil erfollegräich aktualiséiert"
+  },
+  "messages": {
+    "failed_to_load_dashboard_data": "Failed to load dashboard data",
+    "dashboard_refreshed": "Dashboard refreshed"
+  }
+}