Added authentication: Register and Login.

[parth-pawarr]

###Description

1. Added authentication for users, securing the application and restricting access to sensitive routes.
2. Implemented both login and registration flows with clean, modern responsive UI.
3. After successful login, users are routed to a protected dashboard; non-authenticated users are redirected to auth pages.
4. Dashboard displays user-specific data and summary cards, only accessible by authenticated users.

###UI Screenshots

Login Page:

Ensured all sensitive pages are secured and inaccessible to unauthenticated users.
Improved overall UX and visual design to match project branding.