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/order_metrics.py

@@ -302,6 +302,111 @@ class OrderMetricsProvider:
             return []
 
 
+    def get_customer_order_metrics(
+        self,
+        db: Session,
+        vendor_id: int,
+        customer_id: int,
+        context: MetricsContext | None = None,
+    ) -> list[MetricValue]:
+        """
+        Get order metrics for a specific customer.
+
+        This is an entity-level method (not dashboard-level) that provides
+        order statistics for a specific customer. Used by customer detail pages.
+
+        Args:
+            db: Database session
+            vendor_id: Vendor ID (for ownership verification)
+            customer_id: Customer ID
+            context: Optional filtering context
+
+        Returns:
+            List of MetricValue objects for this customer's order activity
+        """
+        from app.modules.orders.models import Order
+
+        try:
+            # Base query for customer orders
+            base_query = db.query(Order).filter(
+                Order.customer_id == customer_id,
+                Order.vendor_id == vendor_id,
+            )
+
+            # Total orders
+            total_orders = base_query.count()
+
+            # Revenue stats
+            revenue_query = db.query(
+                func.sum(Order.total_amount_cents).label("total_spent_cents"),
+                func.avg(Order.total_amount_cents).label("avg_order_cents"),
+                func.max(Order.created_at).label("last_order_date"),
+                func.min(Order.created_at).label("first_order_date"),
+            ).filter(
+                Order.customer_id == customer_id,
+                Order.vendor_id == vendor_id,
+            )
+
+            stats = revenue_query.first()
+
+            total_spent_cents = stats.total_spent_cents or 0
+            avg_order_cents = stats.avg_order_cents or 0
+            last_order_date = stats.last_order_date
+            first_order_date = stats.first_order_date
+
+            # Convert cents to currency
+            total_spent = total_spent_cents / 100
+            avg_order_value = avg_order_cents / 100 if avg_order_cents else 0.0
+
+            return [
+                MetricValue(
+                    key="customer.total_orders",
+                    value=total_orders,
+                    label="Total Orders",
+                    category="customer_orders",
+                    icon="shopping-bag",
+                    description="Total orders placed by this customer",
+                ),
+                MetricValue(
+                    key="customer.total_spent",
+                    value=round(total_spent, 2),
+                    label="Total Spent",
+                    category="customer_orders",
+                    icon="currency-euro",
+                    unit="EUR",
+                    description="Total amount spent by this customer",
+                ),
+                MetricValue(
+                    key="customer.avg_order_value",
+                    value=round(avg_order_value, 2),
+                    label="Avg Order Value",
+                    category="customer_orders",
+                    icon="calculator",
+                    unit="EUR",
+                    description="Average order value for this customer",
+                ),
+                MetricValue(
+                    key="customer.last_order_date",
+                    value=last_order_date.isoformat() if last_order_date else "",
+                    label="Last Order",
+                    category="customer_orders",
+                    icon="calendar",
+                    description="Date of most recent order",
+                ),
+                MetricValue(
+                    key="customer.first_order_date",
+                    value=first_order_date.isoformat() if first_order_date else "",
+                    label="First Order",
+                    category="customer_orders",
+                    icon="calendar-plus",
+                    description="Date of first order",
+                ),
+            ]
+        except Exception as e:
+            logger.warning(f"Failed to get customer order metrics: {e}")
+            return []
+
+
 # Singleton instance
 order_metrics_provider = OrderMetricsProvider()