[FEATURE]: Allow opening skills search with a keybind

[raine]

Feature hasn't been suggested before.

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

Describe the enhancement you want to request

Please allow opening skills search popup with a keybind.

At least https://opencode.ai/docs/keybinds/ does not list skills as possible option for something to add a keybind for.

[github-actions]

For keybind-related issues, please also check our pinned keybinds documentation: #4997