refactor: migrate messaging and media routes to modules

Messaging module (communication):
- vendor_messages.py: Conversation and message management
- vendor_notifications.py: Vendor notifications
- vendor_email_settings.py: SMTP and provider configuration
- vendor_email_templates.py: Email template customization

CMS module (content management):
- vendor_media.py: Media library management
- vendor_content_pages.py: Content page overrides

All routes auto-discovered via is_self_contained=True.
Deleted 5 legacy files from app/api/v1/vendor/.
app/api/v1/vendor/ now empty except for __init__.py (auto-discovery only).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/modules/cms/routes/vendor.py

@@ -2,38 +2,15 @@
 """
 CMS module vendor routes.
 
-This module wraps the existing vendor content pages and media routes
-and adds module-based access control. Routes are re-exported from the
-original location with the module access dependency.
+Re-exports routes from the API routes for backwards compatibility
+with the lazy router attachment pattern.
 
 Includes:
 - /content-pages/* - Content page management
 - /media/* - Media library
 """
 
-from fastapi import APIRouter, Depends
+# Re-export vendor_router from API routes
+from app.modules.cms.routes.api.vendor import vendor_router
 
-from app.api.deps import require_module_access
-
-# Import original routers (direct import to avoid circular dependency)
-from app.api.v1.vendor.content_pages import router as content_original_router
-from app.api.v1.vendor.media import router as media_original_router
-
-# Create module-aware router for content pages
-vendor_router = APIRouter(
-    prefix="/content-pages",
-    dependencies=[Depends(require_module_access("cms"))],
-)
-
-# Re-export all routes from the original content pages module
-for route in content_original_router.routes:
-    vendor_router.routes.append(route)
-
-# Create separate router for media library
-vendor_media_router = APIRouter(
-    prefix="/media",
-    dependencies=[Depends(require_module_access("cms"))],
-)
-
-for route in media_original_router.routes:
-    vendor_media_router.routes.append(route)
+__all__ = ["vendor_router"]