Provide full-screen optimization for Magikeyboard

### Checks

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

### Explain the problem clearly and succinctly:

The small white bar at the bottom of the full-screen display blocks the Magikeyboard buttons, and the rounded corners of the screen now prevent the Magikeyboard from displaying fully.

### Describe the solution you'd like:

Perhaps you could add an option allowing users to choose whether to raise the Magic Keyboard by a certain height from the bottom of the screen; it would be even better if this height were customizable.

### Describe alternatives you've considered:

_No response_

### Additional context:

_No response_

Start by locating the Magikeyboard fullscreen and bottom-inset handling in the Android app, then reproduce the blocked-button and rounded-corner behavior on a fullscreen device. Done means the keyboard remains fully visible and users can choose its bottom offset, including a customizable height.

Written by the indexing model from the issue text.