[Feature]: add a hotkey to select all

[sammaji]

Problem

It would be nice to have a "select all" option.

I know similar issues already exists (e.g. #29)

Proposed Solution

I understand the need for people to be explicit about what skills they are picking, but we still add a hotkey for selecting all skills for those who still don't read before adding skills).

We can either inform the user about it (like adding a text "Space to select, tab to select all") or not inform the user but still have the hotkey.

Alternatives Considered

No response

Additional Context

No response