fix: update user identification method in name change route to use email instead of name

route/conf_name.js

@@ -12,12 +12,12 @@ router.get('/change', (req, res) => {
 
 //사용자 이름 변경(닉네임)
 router.post('/change', async (req, res) => {
-    const { name, newName } = req.body;
+    const { email, newName } = req.body;
 
-    const user = await User.findOne({ name });
+    const user = await User.findOne({ email });
 
     try {
-        if (!name || !newName) {
+        if (!email || !newName) {
             return res.status(400).json({message: '유효하지 않은 요청입니다.'});
         }