feat: 反馈回复通知 + 修复导入

- 管理员回复反馈时自动发送个人通知给用户
- 修复 config.ts 和 feedback.ts 的 pool 导入方式

server/src/routes/config.ts

@@ -1,5 +1,5 @@
 import { Router } from 'express'
-import { pool } from '../db/connection'
+import pool from '../db/connection'
 import { authMiddleware } from '../middleware/auth'
 
 const router = Router()
@@ -37,7 +37,7 @@ router.put('/', authMiddleware, async (req, res) => {
 
     // 批量更新配置
     for (const [key, value] of Object.entries(data)) {
-      await pool.execute(
+      await pool.query(
         'INSERT INTO sys_config (config_key, config_value) VALUES (?, ?) ON DUPLICATE KEY UPDATE config_value = ?',
         [key, value, value]
       )