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/de.json

@@ -0,0 +1,71 @@
+{
+  "dashboard": {
+    "title": "Dashboard",
+    "welcome": "Willkommen zurück",
+    "overview": "Übersicht",
+    "quick_stats": "Schnellstatistiken",
+    "recent_activity": "Letzte Aktivitäten",
+    "total_products": "Produkte gesamt",
+    "total_orders": "Bestellungen gesamt",
+    "total_customers": "Kunden gesamt",
+    "total_revenue": "Gesamtumsatz",
+    "active_products": "Aktive Produkte",
+    "pending_orders": "Ausstehende Bestellungen",
+    "new_customers": "Neue Kunden",
+    "today": "Heute",
+    "this_week": "Diese Woche",
+    "this_month": "Dieser Monat",
+    "this_year": "Dieses Jahr",
+    "error_loading": "Fehler beim Laden des Dashboards",
+    "no_data": "Keine Daten verfügbar"
+  },
+  "settings": {
+    "title": "Einstellungen",
+    "general": "Allgemein",
+    "store": "Shop",
+    "store_name": "Shop-Name",
+    "store_description": "Shop-Beschreibung",
+    "contact_email": "Kontakt-E-Mail",
+    "contact_phone": "Kontakttelefon",
+    "business_address": "Geschäftsadresse",
+    "tax_number": "Steuernummer",
+    "currency": "Währung",
+    "timezone": "Zeitzone",
+    "language": "Sprache",
+    "language_settings": "Spracheinstellungen",
+    "default_language": "Standardsprache",
+    "dashboard_language": "Dashboard-Sprache",
+    "storefront_language": "Shop-Sprache",
+    "enabled_languages": "Aktivierte Sprachen",
+    "notifications": "Benachrichtigungen",
+    "email_notifications": "E-Mail-Benachrichtigungen",
+    "integrations": "Integrationen",
+    "api_keys": "API-Schlüssel",
+    "webhooks": "Webhooks",
+    "save_settings": "Einstellungen speichern",
+    "settings_saved": "Einstellungen erfolgreich gespeichert"
+  },
+  "profile": {
+    "title": "Profil",
+    "my_profile": "Mein Profil",
+    "edit_profile": "Profil bearbeiten",
+    "personal_info": "Persönliche Informationen",
+    "first_name": "Vorname",
+    "last_name": "Nachname",
+    "email": "E-Mail",
+    "phone": "Telefon",
+    "avatar": "Profilbild",
+    "change_avatar": "Profilbild ändern",
+    "security": "Sicherheit",
+    "two_factor": "Zwei-Faktor-Authentifizierung",
+    "sessions": "Aktive Sitzungen",
+    "preferences": "Präferenzen",
+    "language_preference": "Sprachpräferenz",
+    "save_profile": "Profil speichern",
+    "profile_updated": "Profil erfolgreich aktualisiert"
+  },
+  "messages": {
+    "failed_to_load_dashboard_data": "Failed to load dashboard data",
+    "dashboard_refreshed": "Dashboard refreshed"
+  }
+}