fix: add missing get_vendors_with_orders_admin method

Add the missing method to OrderService that was being called
from the admin orders API endpoint.

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

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

app/services/order_service.py

@@ -1008,6 +1008,34 @@ class OrderService:
 
         return order
 
+    def get_vendors_with_orders_admin(self, db: Session) -> list[dict]:
+        """Get list of vendors that have orders (admin only)."""
+        from models.database.vendor import Vendor
+
+        # Query vendors with order counts
+        results = (
+            db.query(
+                Vendor.id,
+                Vendor.name,
+                Vendor.vendor_code,
+                func.count(Order.id).label("order_count"),
+            )
+            .join(Order, Order.vendor_id == Vendor.id)
+            .group_by(Vendor.id, Vendor.name, Vendor.vendor_code)
+            .order_by(func.count(Order.id).desc())
+            .all()
+        )
+
+        return [
+            {
+                "id": row.id,
+                "name": row.name,
+                "vendor_code": row.vendor_code,
+                "order_count": row.order_count,
+            }
+            for row in results
+        ]
+
 
 # Create service instance
 order_service = OrderService()