refactor: fix architecture violations with provider patterns and dependency inversion

Major changes:
- Add AuditProvider protocol for cross-module audit logging
- Move customer order operations to orders module (dependency inversion)
- Add customer order metrics via MetricsProvider pattern
- Fix missing db parameter in get_admin_context() calls
- Move ProductMedia relationship to catalog module (proper ownership)
- Add marketplace breakdown stats to marketplace_widgets

New files:
- contracts/audit.py - AuditProviderProtocol
- core/services/audit_aggregator.py - Aggregates audit providers
- monitoring/services/audit_provider.py - Monitoring audit implementation
- orders/services/customer_order_service.py - Customer order operations
- orders/routes/api/vendor_customer_orders.py - Customer order endpoints
- catalog/services/product_media_service.py - Product media service
- Architecture documentation for patterns

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

app/modules/orders/routes/api/vendor.py

@@ -284,6 +284,9 @@ def ship_order_item(
 # ============================================================================
 
 # Import sub-routers
+from app.modules.orders.routes.api.vendor_customer_orders import (
+    vendor_customer_orders_router,
+)
 from app.modules.orders.routes.api.vendor_exceptions import vendor_exceptions_router
 from app.modules.orders.routes.api.vendor_invoices import vendor_invoices_router
 
@@ -291,3 +294,4 @@ from app.modules.orders.routes.api.vendor_invoices import vendor_invoices_router
 vendor_router.include_router(_orders_router, tags=["vendor-orders"])
 vendor_router.include_router(vendor_exceptions_router, tags=["vendor-order-exceptions"])
 vendor_router.include_router(vendor_invoices_router, tags=["vendor-invoices"])
+vendor_router.include_router(vendor_customer_orders_router, tags=["vendor-customer-orders"])