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/services/__init__.py

@@ -25,6 +25,10 @@ from app.modules.orders.services.invoice_pdf_service import (
     invoice_pdf_service,
     InvoicePDFService,
 )
+from app.modules.orders.services.customer_order_service import (
+    customer_order_service,
+    CustomerOrderService,
+)
 
 __all__ = [
     "order_service",
@@ -37,4 +41,6 @@ __all__ = [
     "InvoiceService",
     "invoice_pdf_service",
     "InvoicePDFService",
+    "customer_order_service",
+    "CustomerOrderService",
 ]