完善配送合同关联信息展示与归属校验

三端合同页面改为优先显示用户、气站和配送点业务名称，并保留标识与合同编号复制能力。

平台端增加气站与直属配送点联动，后端禁止平台主管及跨气站配送点绑定合同，同时补充测试和中文文档。

backend/api/internal/logic/platform/gasorder/gasorder.go

@@ -739,7 +739,12 @@ func deliveryBelongsToGas(deliveryID, gasID uint64) bool {
 	}
 	var delivery models.DeliveryBasic
 	return impl.DBService.Select("gas_basic_id").First(&delivery, deliveryID).Error == nil &&
-		(delivery.GasBasicID == 0 || delivery.GasBasicID == gasID)
+		contractDeliveryMatchesGas(delivery.GasBasicID, gasID)
+}
+
+// contractDeliveryMatchesGas 校验合同配送点必须直属于合同气站；平台主管配送点不能绑定到气站合同。
+func contractDeliveryMatchesGas(deliveryGasID, contractGasID uint64) bool {
+	return deliveryGasID != 0 && deliveryGasID == contractGasID
 }
 
 func gasorderStatusRecord(orderID uint64, from, to int, reason, operatorIdentity, operatorName string) *models.GasorderStatus {

backend/api/internal/logic/platform/gasorder/gasorder_test.go

@@ -106,6 +106,18 @@ func TestContractRevisionKeepsSingleContractHistory(t *testing.T) {
 	}
 }
 
+func TestContractDeliveryRequiresDirectGasOwnership(t *testing.T) {
+	if !contractDeliveryMatchesGas(10, 10) {
+		t.Fatal("合同气站的直属配送点被错误拒绝")
+	}
+	if contractDeliveryMatchesGas(0, 10) {
+		t.Fatal("平台主管配送点不应绑定到气站合同")
+	}
+	if contractDeliveryMatchesGas(11, 10) {
+		t.Fatal("其他气站配送点不应绑定到当前气站合同")
+	}
+}
+
 func TestGasorderSensitiveContactsAreMasked(t *testing.T) {
 	value := map[string]any{
 		"contact_name":    "张三",