fix: remove stale admin_servers column reference from users UPDATE

backend/routes/users.js

@@ -41,7 +41,6 @@ router.put('/:id', authenticate, requireRole('owner','admin'), async (req, res)
   if (req.body.game_name) fields.game_name = req.body.game_name;
   if (req.body.game_uid) fields.game_uid = req.body.game_uid;
   if (req.body.source) { if (!['netease','skin'].includes(req.body.source)) return res.status(400).json({ error: '无效来源' }); fields.source = req.body.source; }
-  if (req.body.admin_servers !== undefined) fields.admin_servers = JSON.stringify(req.body.admin_servers);
   if (req.body.role) { if (!['owner','admin','player'].includes(req.body.role)) return res.status(400).json({ error: '无效角色' }); fields.role = req.body.role; }
   if (req.body.active !== undefined) fields.active = req.body.active ? 1 : 0;
   if (req.body.password) { if (req.body.password.length < 6) return res.status(400).json({ error: '密码至少6位' }); fields.password = bcrypt.hashSync(req.body.password, 10); }