Implement Protected Routes Middleware

[Hamzaa6296]

Description:

What needs to be done

• Create auth middleware in Next.js
• Check JWT token on protected routes
• Redirect to /login if not authenticated
• Redirect to /dashboard if already logged in
• Handle token expiry gracefully

Acceptance Criteria

• Unauthenticated users redirected to login
• Logged in users cant access /login or /signup
• Expired token redirects to login
• Works with Next.js App Router