Issue #1: Implement JWT Authentication and Role-Based Access Control (RBAC)

[PRIYANSHU2026]

Description:
Currently, the application relies on a mock authentication system where the user simply selects their role from a sidebar dropdown (render_sidebar_auth). For a production banking module, we need a secure, token-based authentication system to protect sensitive loan data and restrict model training capabilities.

Tasks & Implementation Details:

• Backend:
  • Create a new User SQLAlchemy model with fields: id, username, hashed_password, role (Customer, Loan Officer, Administrator).
  • Implement password hashing using passlib and bcrypt.
  • Create an OAuth2 login endpoint (/api/token) that verifies credentials and returns a JSON Web Token (JWT) using the PyJWT library.
  • Create a get_current_user dependency in FastAPI to secure sensitive endpoints (e.g., only Administrators can hit /api/models/reload).
• Frontend:
  • Build a Streamlit Login/Registration page that prompts for a username and password.
  • Store the retrieved JWT in Streamlit's st.session_state.
  • Update all requests.get() and requests.post() calls in the dashboard to include {"Authorization": f"Bearer {token}"} in the headers.

Acceptance Criteria:

• Users must log in to access the dashboard.
• The backend rejects unauthorized API requests with a 401 Unauthorized.
• Roles are strictly enforced (e.g. Customers cannot view the Model Training page).

Assignee : @Rishabh02-rgb