No option to remove credentials on iOS

[derblack70]

Platform:
iOS (tested with [insert your iOS version])

App Version:
0.22.0 (latest from App Store)

Issue Description:
After successfully connecting the app to a Firefly III backend using a personal access token, there is no way to remove or reset the stored connection. Even after:
• Deleting the app
• Disabling iCloud Keychain
• Restarting the device
• Reinstalling the app

…the previously entered backend URL and credentials are still retained.

This suggests the app is storing the credentials in the local iOS Keychain in a way that survives uninstallation, without offering the user any way to remove them from within the app.

Expected Behavior

The app should offer a way to:
• Log out or disconnect from the current Firefly instance
• Delete stored credentials
• Reset the app to initial state

(ideally under “Settings → Manage login information”)

Suggestions
• Add a “Sign out” or “Reset App” button
• Provide an option to clear all secure storage
• Ensure stored credentials are removed upon app deletion (opt-in)

Security & Privacy Concern
From a user perspective, it is unexpected that credentials persist after app deletion, especially when iCloud Keychain has been disabled. This could pose a privacy risk in shared-device scenarios.

Thank you for the great work on this app – it works very well overall!
This enhancement would make the experience more privacy-friendly and user-friendly. 🙏