fix: duplicate res.json crash + missing try/catch in bans POST

backend/routes/bans.js

@@ -27,6 +27,7 @@ router.get('/min-duration', authenticate, async (req, res) => {
 });
 
 router.post('/', authenticate, requireRole('owner'), async (req, res) => {
+  try {
     const { player_name, player_uid, reason, type, duration, ticket_id, expires_at, source } = req.body;
     if (!player_name) return res.status(400).json({ error: '玩家名为必填' });
 
@@ -44,7 +45,10 @@ router.post('/', authenticate, requireRole('owner'), async (req, res) => {
         [ticket_id, req.user.id, `【处罚记录】${type==='ban'?'封禁':type==='mute'?'禁言':type==='warn'?'警告':'其他'}: ${player_name}${duration?' 时长:'+duration:''}${reason?' 原因:'+reason:''}`]);
     }
     res.status(201).json({ id: r.insertId });
-  res.status(201).json({ id: r.insertId });
+  } catch (err) {
+    console.error('[bans]', err);
+    res.status(500).json({ error: '添加失败: ' + err.message });
+  }
 });
 
 router.put('/:id', authenticate, requireRole('owner'), async (req, res) => {