P0-S1-001: Fix End-to-End Authentication Flow

[Reg-Kris]

User Story

As a user, I need to successfully authenticate so I can access the PyAirtable features.

Current State

• Frontend login form exists but doesn't connect to backend
• Authentication service running on port 7007 but not properly integrated
• JWT token generation/validation not working end-to-end
• CORS issues preventing frontend-backend communication

Acceptance Criteria

• Frontend login form connects to backend auth service on port 7007
• JWT tokens are properly generated and validated
• Session management working between frontend (port 5173) and backend
• Error handling for invalid credentials with user-friendly messages
• Protected routes redirect unauthenticated users to login
• Token refresh mechanism prevents session expiration
• CORS configuration allows frontend-backend communication

Branch Name

fix/authentication-flow

Story Points

8 (Complex integration between frontend and backend)

Dependencies

• Platform services must be running and healthy
• Database connection for user storage
• Redis for session management