Feat: Change App Structure

Major Refactor

This PR includes the following changes:

Migrated to Next.js App Router: The application's file structure has been updated to use the new Next.js App Router, which provides improved routing and server-side rendering capabilities.
Integrated TypeScript: The project has been converted to use TypeScript, improving the codebase's type-safety and developer experience.
Implemented Axios Client Utilities: New utility functions have been added to set up an Axios client, handle authentication tokens, and provide an authenticated API instance.
Implemented Auth Guard: An authentication guard has been implemented to protect routes and ensure only authenticated users can access certain parts of the application.

Updated the file structure to use the Next.js App Router.
Converted the codebase to TypeScript.
Created an Axios client utility module that handles token management and provides an authenticated API instance.
Implemented an auth guard to protect routes and ensure only authenticated users can access certain parts of the application.

The migration to the Next.js App Router provides improved routing and server-side rendering, enhancing the overall application performance and user experience.
TypeScript integration enhances code maintainability, reduces bugs, and improves the developer experience.
The Axios client utilities streamline API interactions and ensure consistent token management across the application.
The auth guard protects sensitive routes and ensures only authorized users can access restricted areas of the application.

All existing tests have been updated and are passing.
Manual testing has been performed to ensure the application functions as expected with the new changes.