API Endpoints
POST/api/login
Login — no rate limiting. Body: {"username":"alice","password":"alice123"}
Lab Credentials: ram / pracivo | alice / alice123 | bob / bob456 | admin / adminpass
GET/api/user/<id>
Get user data — IDOR: no ownership check. Try /api/user/1, /api/user/2, /api/user/3
GET/api/messages/<user_id>
Get messages — IDOR: change user_id to read other users messages
GET/api/profile
Get own profile using token header — token is just base64(user_id)
GET/api/admin/users
Admin endpoint — no auth check. Lists all users with passwords.