feat(discount): calculate_product_cost 接入客户折扣

成交价 = 资源真实定价 × 客户折扣（照 llmage 范式 get_customer_discount）
返回 amount(成交价)/original_amount(原价)/discount(折扣率)

account_resource/product_interface.py

@@ -173,5 +173,18 @@ async def calculate_product_cost(resource_ref_id, usage_data, user_org_id=None):
         return {'success': False, 'message': '定价计算失败: %s' % e}
 
     amount = sum(getattr(p, 'amount', 0) for p in prices)
-    return {'success': True, 'amount': amount, 'original_amount': amount,
-            'cost': 0.0, 'discount': 1.0, 'pricing_program_id': ppid}
+
+    # 客户折扣：资源真实定价 × 客户折扣 = 成交价（照 llmage 范式）
+    discount = 1.0
+    if user_org_id:
+        try:
+            d = await env.get_customer_discount(
+                getattr(spec, 'org_id', '') or '0', user_org_id)
+            if d not in (None, '', 0):
+                discount = float(d)
+        except Exception:
+            discount = 1.0
+
+    return {'success': True, 'amount': round(amount * discount, 6),
+            'original_amount': round(amount, 6),
+            'cost': 0.0, 'discount': discount, 'pricing_program_id': ppid}