- Added support for refresh tokens in the authentication backend, allowing users to obtain new access tokens using valid refresh tokens.
- Created a new `BearerResponseWithRefresh` model to structure responses containing both access and refresh tokens.
- Updated the `AuthenticationBackend` to handle login and logout processes with refresh token support.
- Introduced a new `/auth/jwt/refresh` endpoint to facilitate token refreshing, validating the refresh token and generating new tokens as needed.
- Modified OAuth callback logic to generate and return both access and refresh tokens upon successful authentication.
- Updated frontend API service to send the refresh token in the Authorization header for token refresh requests.
