feat: add marketplace products admin UI with copy-to-vendor functionality

- Add admin marketplace products page to browse imported products
- Add admin vendor products page to manage vendor catalog
- Add product detail pages for both marketplace and vendor products
- Implement copy-to-vendor API to copy marketplace products to vendor catalogs
- Add vendor product service with CRUD operations
- Update sidebar navigation with new product management links
- Add integration and unit tests for new endpoints and services

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/api/v1/admin/__init__.py

@@ -35,9 +35,11 @@ from . import (
     marketplace,
     monitoring,
     notifications,
+    products,
     settings,
     users,
     vendor_domains,
+    vendor_products,
     vendor_themes,
     vendors,
 )
@@ -92,6 +94,17 @@ router.include_router(users.router, tags=["admin-users"])
 router.include_router(dashboard.router, tags=["admin-dashboard"])
 
 
+# ============================================================================
+# Product Catalog
+# ============================================================================
+
+# Include marketplace product catalog management endpoints
+router.include_router(products.router, tags=["admin-marketplace-products"])
+
+# Include vendor product catalog management endpoints
+router.include_router(vendor_products.router, tags=["admin-vendor-products"])
+
+
 # ============================================================================
 # Marketplace & Imports
 # ============================================================================