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/messaging/static/admin/js/email-templates.js

@@ -51,6 +51,9 @@ function emailTemplatesPage() {
 
         // Lifecycle
         async init() {
+            // Load i18n translations
+            await I18n.loadModule('messaging');
+
             if (window._adminEmailTemplatesInitialized) return;
             window._adminEmailTemplatesInitialized = true;
 
@@ -70,7 +73,7 @@ function emailTemplatesPage() {
                 this.categories = categoriesData.categories || [];
             } catch (error) {
                 emailTemplatesLog.error('Failed to load email templates:', error);
-                Utils.showToast('Failed to load templates', 'error');
+                Utils.showToast(I18n.t('messaging.messages.failed_to_load_templates'), 'error');
             } finally {
                 this.loading = false;
             }
@@ -122,10 +125,10 @@ function emailTemplatesPage() {
                         variables: [],
                         required_variables: []
                     };
-                    Utils.showToast(`No template for ${this.editLanguage.toUpperCase()} - create one by saving`, 'info');
+                    Utils.showToast(I18n.t('messaging.messages.no_template_for_language', { language: this.editLanguage.toUpperCase() }), 'info');
                 } else {
                     emailTemplatesLog.error('Failed to load template:', error);
-                    Utils.showToast('Failed to load template', 'error');
+                    Utils.showToast(I18n.t('messaging.messages.failed_to_load_template'), 'error');
                 }
             } finally {
                 this.loadingTemplate = false;
@@ -158,12 +161,12 @@ function emailTemplatesPage() {
                     }
                 );
 
-                Utils.showToast('Template saved successfully', 'success');
+                Utils.showToast(I18n.t('messaging.messages.template_saved_successfully'), 'success');
                 // Refresh templates list
                 await this.loadData();
             } catch (error) {
                 emailTemplatesLog.error('Failed to save template:', error);
-                Utils.showToast(error.detail || 'Failed to save template', 'error');
+                Utils.showToast(error.detail || I18n.t('messaging.messages.failed_to_save_template'), 'error');
             } finally {
                 this.saving = false;
             }
@@ -188,7 +191,7 @@ function emailTemplatesPage() {
                 this.showPreviewModal = true;
             } catch (error) {
                 emailTemplatesLog.error('Failed to preview template:', error);
-                Utils.showToast('Failed to load preview', 'error');
+                Utils.showToast(I18n.t('messaging.messages.failed_to_load_preview'), 'error');
             }
         },
 
@@ -250,15 +253,15 @@ function emailTemplatesPage() {
                 );
 
                 if (result.success) {
-                    Utils.showToast(`Test email sent to ${this.testEmailAddress}`, 'success');
+                    Utils.showToast(I18n.t('messaging.messages.test_email_sent', { email: this.testEmailAddress }), 'success');
                     this.showTestEmailModal = false;
                     this.testEmailAddress = '';
                 } else {
-                    Utils.showToast(result.message || 'Failed to send test email', 'error');
+                    Utils.showToast(result.message || I18n.t('messaging.messages.failed_to_send_test_email'), 'error');
                 }
             } catch (error) {
                 emailTemplatesLog.error('Failed to send test email:', error);
-                Utils.showToast('Failed to send test email', 'error');
+                Utils.showToast(I18n.t('messaging.messages.failed_to_send_test_email'), 'error');
             } finally {
                 this.sendingTest = false;
             }