- Added Profile and ProfileList structs to manage user profiles with unique IDs and nicknames.
- Introduced endpoints for CRUD operations on profiles: `/api/profiles` for managing profiles and `/api/profiles/switch` for switching active profiles.
- Implemented settings management with an endpoint `/api/settings` to handle user preferences like font size and debug mode.
- Enhanced the server to load and save profiles from a `profiles.json` file.
- Updated the fetcher initialization to respect the active profile's configuration.
- Added comprehensive end-to-end tests for profiles and settings APIs to ensure functionality and persistence.