fix: Correct variable references in PO seed script

Fixed 'items' is not defined error in demo seed script:
- Changed 'items' references to 'items_data' (the function parameter)
- Updated product_names extraction to use dict.get() for safety
- Fixed create_po_reasoning_supplier_contract call to use correct parameters
  (contract_quantity instead of trust_score)

This resolves the warnings about failed reasoning_data generation
during purchase order seeding.

services/procurement/scripts/demo/seed_demo_purchase_orders.py

@@ -128,10 +128,11 @@ async def create_purchase_order(
     reasoning_data = None
 
     try:
-        # Get product names from items
-        product_names = [item.product_name for item in items if hasattr(item, 'product_name')]
+        # Get product names from items_data
+        items_list = items_data or []
+        product_names = [item.get('product_name', f"Product {i+1}") for i, item in enumerate(items_list)]
         if not product_names:
-            product_names = [f"Product {i+1}" for i in range(len(items))]
+            product_names = ["Demo Product"]
 
         if status == PurchaseOrderStatus.pending_approval:
             # Low stock detection reasoning
@@ -151,8 +152,8 @@ async def create_purchase_order(
             reasoning_data = create_po_reasoning_supplier_contract(
                 supplier_name=supplier.name,
                 product_names=product_names,
-                contract_terms=f"Auto-approval threshold: €500",
-                trust_score=float(supplier.trust_score) if hasattr(supplier, 'trust_score') else 0.85
+                contract_terms="monthly",
+                contract_quantity=float(total_amount)
             )
     except Exception as e:
         logger.warning(f"Failed to generate reasoning_data: {e}")