Audio: text attributes focus bookmark PoC

[lexiv0re]

Motivation and context

Typing in a textarea disables app shortcuts to avoid breaking normal text editing. It makes it harder to control the audio (seek/playblack).

Allowing individual shortcuts inside inputs is unsafe: user-configured bindings can conflict with typing, selection, or native controls. For play/pause which is space by default, even combinations of space with modifier keys are widely used and represent system shortcuts for system menus and operations.

This PoC introduces a concept of focus bookmark:
Press Esc in a textarea to blur it and leave a caret bookmark. App shortcuts become available; use them to navigate or control playback. In Cursor mode, press Esc again to restore focus at the bookmarked caret position and continue typing.

Real scenario:

1. Create an interval
2. Listen to the first part
3. Type transcription into the transcription field
4. Click Esc to leave a focus bookmark and make shortcuts available
5. Click space to listen to the next part of the interval, click space again to stop the playback
6. Click Esc to return to the previously focused position within the textarea
7. Type new portion of the transcription
8. Repeat steps 4-7 until the interval is fully transcribed.

It allows to implement this scenario without using mouse at all, making such transcription faster.

How focus bookmark looks like:

Note: hovering over it displays the help tooltip on how it operates.

How has this been tested?

Tested manually

Checklist

• I submit my changes into the develop branch
• I have created a changelog fragment
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have linked related issues (see GitHub docs)

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.