[FEATURE] Add Ctrl+J/Ctrl+K navigation in menu bar (Vim-friendly)

[muzig]

Feature hasn't been suggested before.

• [x] I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

What do you want to change or add? Add Vim-style keyboard navigation support to the project's menu bar (e.g., the "Commands" panel in the attached screenshot):

• Bind Ctrl+K to move upward between menu options
• Bind Ctrl+J to move downward between menu options

What are the benefits of implementing this?

1. Improves efficiency for Vim developers: they can navigate menus without switching to mouse/other keys, keeping a keyboard-first workflow
2. Enhances accessibility for a common developer group (Vim users), reducing friction when using the project's interface