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/inventory/locales/de.json

@@ -1 +1,22 @@
-{}
+{
+  "inventory": {
+    "title": "Inventar",
+    "stock_level": "Lagerbestand",
+    "quantity": "Menge",
+    "reorder_point": "Nachbestellpunkt",
+    "adjust_stock": "Bestand anpassen",
+    "stock_in": "Wareneingang",
+    "stock_out": "Warenausgang",
+    "transfer": "Transfer",
+    "history": "Verlauf",
+    "low_stock_alert": "Warnung bei geringem Bestand",
+    "out_of_stock_alert": "Warnung bei Ausverkauf"
+  },
+  "messages": {
+    "stock_adjusted_successfully": "Stock adjusted successfully",
+    "quantity_set_successfully": "Quantity set successfully",
+    "inventory_entry_deleted": "Inventory entry deleted.",
+    "please_select_a_vendor_and_file": "Please select a vendor and file",
+    "import_completed_with_errors": "Import completed with errors"
+  }
+}

app/modules/inventory/locales/en.json

@@ -1 +1,31 @@
-{}
+{
+  "inventory": {
+    "title": "Inventory",
+    "stock_level": "Stock Level",
+    "quantity": "Quantity",
+    "reorder_point": "Reorder Point",
+    "adjust_stock": "Adjust Stock",
+    "stock_in": "Stock In",
+    "stock_out": "Stock Out",
+    "transfer": "Transfer",
+    "history": "History",
+    "low_stock_alert": "Low Stock Alert",
+    "out_of_stock_alert": "Out of Stock Alert"
+  },
+  "messages": {
+    "stock_adjusted_successfully": "Stock adjusted successfully",
+    "quantity_set_successfully": "Quantity set successfully",
+    "inventory_entry_deleted": "Inventory entry deleted.",
+    "please_select_a_vendor_and_file": "Please select a vendor and file",
+    "import_completed_with_errors": "Import completed with errors",
+    "failed_to_adjust_stock": "Failed to adjust stock.",
+    "failed_to_set_quantity": "Failed to set quantity.",
+    "failed_to_delete_entry": "Failed to delete entry.",
+    "import_success": "Imported {quantity} units ({created} new, {updated} updated)",
+    "import_completed": "Import completed: {created} created, {updated} updated, {errors} errors",
+    "import_failed": "Import failed",
+    "bulk_adjust_success": "{count} item(s) adjusted by {amount}",
+    "failed_to_adjust_inventory": "Failed to adjust inventory",
+    "exported_items": "Exported {count} item(s)"
+  }
+}

app/modules/inventory/locales/fr.json

@@ -1 +1,22 @@
-{}
+{
+  "inventory": {
+    "title": "Inventaire",
+    "stock_level": "Niveau de stock",
+    "quantity": "Quantité",
+    "reorder_point": "Seuil de réapprovisionnement",
+    "adjust_stock": "Ajuster le stock",
+    "stock_in": "Entrée de stock",
+    "stock_out": "Sortie de stock",
+    "transfer": "Transfert",
+    "history": "Historique",
+    "low_stock_alert": "Alerte stock faible",
+    "out_of_stock_alert": "Alerte rupture de stock"
+  },
+  "messages": {
+    "stock_adjusted_successfully": "Stock adjusted successfully",
+    "quantity_set_successfully": "Quantity set successfully",
+    "inventory_entry_deleted": "Inventory entry deleted.",
+    "please_select_a_vendor_and_file": "Please select a vendor and file",
+    "import_completed_with_errors": "Import completed with errors"
+  }
+}

app/modules/inventory/locales/lb.json

@@ -1 +1,22 @@
-{}
+{
+  "inventory": {
+    "title": "Inventar",
+    "stock_level": "Lagerniveau",
+    "quantity": "Quantitéit",
+    "reorder_point": "Nobestellungspunkt",
+    "adjust_stock": "Lager upaassen",
+    "stock_in": "Lager eran",
+    "stock_out": "Lager eraus",
+    "transfer": "Transfer",
+    "history": "Geschicht",
+    "low_stock_alert": "Niddreg Lager Alarm",
+    "out_of_stock_alert": "Net op Lager Alarm"
+  },
+  "messages": {
+    "stock_adjusted_successfully": "Stock adjusted successfully",
+    "quantity_set_successfully": "Quantity set successfully",
+    "inventory_entry_deleted": "Inventory entry deleted.",
+    "please_select_a_vendor_and_file": "Please select a vendor and file",
+    "import_completed_with_errors": "Import completed with errors"
+  }
+}