Develop and connect Backend to frontend

[Katijino]

2. Backend (Node.js + Express) Development
   Goal: Build API routes to interact with your frontend.
   Steps:
   Set up a simple Node.js and Express server.
   Create basic API routes (e.g., /daily-stat, /submit-guess, /user-profile).
   Implement the logic for retrieving and processing mock data (later replaced with real database queries).