Axios config

[Cry199]

This pull request introduces improved error handling for invalid JWT tokens in the backend, and enhances the frontend to better handle authentication errors by redirecting users to the login page when their token is invalid or expired. Additionally, it updates the frontend API base URL.

Backend: Improved Token Error Handling

• Added a custom exception InvalidTokenException for clearer handling of invalid or expired JWT tokens. (linktreeclone-backend/src/main/java/br/com/linktreeclone/exception/InvalidTokenException.java, linktreeclone-backend/src/main/java/br/com/linktreeclone/exception/InvalidTokenException.javaR1-R8)
• Updated the TokenService to throw InvalidTokenException instead of a generic RuntimeException when token validation fails. (linktreeclone-backend/src/main/java/br/com/linktreeclone/security/TokenService.java, [1] [2]
• Modified RestExceptionHandler to handle InvalidTokenException and return a 403 Forbidden response with a descriptive error. (linktreeclone-backend/src/main/java/br/com/linktreeclone/exception/RestExceptionHandler.java, linktreeclone-backend/src/main/java/br/com/linktreeclone/exception/RestExceptionHandler.javaR41-R52)

Frontend: Authentication Error Handling and Configuration

• Updated the API base URL to the new backend endpoint. (linktreeclone-frontend/src/api/axiosConfig.js, linktreeclone-frontend/src/api/axiosConfig.jsL4-R4)
• Added a response interceptor to catch 401 and 403 errors, clear the authentication token, and redirect the user to the login page, improving the user experience on session expiry or invalid token. (linktreeclone-frontend/src/api/axiosConfig.js, linktreeclone-frontend/src/api/axiosConfig.jsR18-R31)