Style dialog - Enter does not activate OK button, Tab does not move focus to the button group

Issue type

Accessibility issue (e.g. for keyboard-only or screen reader users)

Bug description

Enter does not operate the OK button in the Style dialog, making it difficult to operate with keyboard only. Alt+O does work on Linux but apparently not on all systems.

Compounding this, the Style dialog is still using the old navigation scheme where Tab moves to the next field instead of the next group. This is actually one of the few dialogs complex enough that really would benefit from the hierarchical navigation. I assume that requires porting to QML, but fixing Enter should be doable as a quick fix.

Worse, the dialog is large enough that it does not fit on some displays, cutting off the visibility of the OK and Cancel buttons. This leads to a lot of people closing via Esc or the "X" on the title bar, then wondering why their changes don't stick.

Steps to reproduce

1. Format / Style
2. Change any style value
3. Press Tab
4. Press Enter

Result: dialog is not closed

5. Press Tab

Result: focus moves to next field instead of to button row

Screenshots/Screen recordings

No response

MuseScore Version

OS: Debian GNU/Linux 12 (bookworm), Arch.: x86_64, MuseScore version (64-bit): 4.2.1-240230938, revision: github-musescore-musescore-d757433

Regression

Yes, this used to work in MuseScore 3.x and now is broken

Operating system

Debian 12

Additional context

No response