fix(order): 前置余额扣减并统一金额精度处理，补充余额校验与单测

- 抽取 validateSufficientBalance，统一使用 normalizeMoney 校验与比较，提升健壮性\n- AbstractOrderPlacementStrategy：在创建订单前根据 shouldDeduct 进行余额校验与扣减，使用上下文 orderId 记录流水，避免不一致\n- deductCustomerBalance：使用 amountToDeduct 变量并先归一化后运算，修正可能的精度问题\n- 调整/补充测试用例：扣减失败不插入订单、不保存用户信息；更新 selectById 调用次数校验

play-admin/src/test/java/com/starry/admin/modules/order/service/impl/OrderLifecycleServiceImplTest.java

@@ -733,6 +733,8 @@ private PlayOrderLogInfoMapper orderLogInfoMapper;
 
         assertThrows(ServiceException.class, () -> lifecycleService.placeOrder(command));
         verify(customUserInfoService, never()).updateAccountBalanceById(anyString(), any(), any(), anyString(), anyString(), any(), any(), anyString());
+        verify(orderInfoMapper, never()).insert(any());
+        verify(customUserInfoService, never()).saveOrderInfo(any());
     }
 
     @Test
@@ -863,6 +865,8 @@ private PlayOrderLogInfoMapper orderLogInfoMapper;
                 null);
 
         assertThrows(ServiceException.class, () -> lifecycleService.placeOrder(command));
+        verify(orderInfoMapper, never()).insert(any());
+        verify(customUserInfoService, never()).saveOrderInfo(any());
     }
 
     @Test
@@ -962,7 +966,7 @@ private PlayOrderLogInfoMapper orderLogInfoMapper;
                 null,
                 null));
 
-        verify(customUserInfoService).selectById(context.getPurchaserBy());
+        verify(customUserInfoService, times(2)).selectById(context.getPurchaserBy());
         verify(customUserInfoService).updateAccountBalanceById(
                 eq(customer.getId()),
                 eq(customer.getAccountBalance()),