🔧 Fix:
- Use req.body directly instead of req.text() + JSON.parse()
- Match pattern used in working auth endpoints
- Should resolve NOT_FOUND and parsing issues
🔧 Admin Management:
- Add api/admin/promote-user.js endpoint
- Allows promoting users to admin role by username or userId
- Checks for existing admin status
- Returns updated user info with roles
- Handles database errors gracefully
Usage: POST /api/admin/promote-user with { username: 'testuser' }