- Bumped APP_VERSION to 0.8.136 and updated the changelog to reflect recent changes.
- Fixed the Mandanten-Header handling in `api/exercises.js` for improved API requests.
- Continued Frontend Phase 4 with the addition of the `exercises.js` module, enhancing the API structure.
- Updated architecture documentation to include details on the new `exercises.js` API and its integration with the existing client structure.
- Enhanced `utils/api.js` to re-export the new exercises module, streamlining API access.
