No longer able to access on-device passkeys when KeePassDX is set as sign-in service

### Checks

- [x] I have read the Wiki, searched the open issues, and still think this is a new bug.

### Explain the problem clearly and succinctly:

Hello

I have passkeys stored on-device only (without synchronisation) and use KeePassDX to store passwords. This worked well until KeePassDX introduced support for passkeys. Now, if i want to log in somewhere with a passkey, KeePassDX opens and i can no longer access my on-device passkeys.

The only workaround is to change in Android's settings, under "Passwords, passkeys and accounts" the "Preferred service" from "KeePassDX" to "None" and, after logging in, back to "KeePassDX". However, this is very cumbersome.

I don't know if this this is a problem that KeePassDX can solve or if this is a problem of Android. In the first case, I would greatly appreciate it if you could add an option to disable passkeys in KeePassDX.

### Describe what you expected to happen:

_No response_

### KeePassDX version:

4.2.4

### Build:

Free

### Database version:

_No response_

### File provider (`content://` URI)

_No response_

### Android version:

16

### Android device:

Google Pixel 7a

### Additional context:

_No response_

Start by reproducing the passkey flow on Android 16 with KeePassDX 4.2.4, using a Pixel 7a or equivalent setup. Compare behavior with KeePassDX selected and with None selected as the preferred service, then determine whether the fix belongs in KeePassDX's passkey integration or Android's credential-provider behavior. Done means on-device passkeys remain accessible without repeatedly changing the preferred service.

Written by the indexing model from the issue text.