Reauthentication Workflow for Unauthorized Error

## Summary
When a user encounters an "Unauthorized" error while attempting to access their vault through the Files app, they should be guided through a reauthentication workflow via deep-linking.

## Details
Upon receiving an "Unauthorized" message, the user will be presented with an option to initiate reauthentication.

Selecting the reauthentication option will deep-link the user to Cryptomator's main app, where the authentication process will start automatically.

This will provide a seamless way for users to restore access without needing to manually navigate through the app settings.

### User Flow
1. User attempts to access their vault via the Files app, but the cloud access token is invalid.
2. "UnauthorizedError" screen appears with an option to reauthenticate.
3. User selects "Open Cryptomator".
4. Cryptomator app opens via deep-link, automatically starting the authentication process.

## Notes
This enhancement is a follow-up from #18.

Start with the UnauthorizedError screen in the Files app and the deep-link entry point in Cryptomator's main app. Trace how an invalid cloud access token reaches the screen and how authentication currently starts. Done means the user can select "Open Cryptomator," launch the main app through a deep link, and have authentication start automatically.

Written by the indexing model from the issue text.