Add 10 personalized commands

Allow the user to define commands that will run pressing any keyboard number (from 1 to 0) during a Pomodoro/break.

That way, a user could define/press "1" to pause the music and open Jitsy Meet to jump on a call, for example.

Allow them to run a few internal functions, as pause and/or restart.

The issue does not name files, tests, or an entry point, so first locate the Pomodoro/break keyboard handling and any existing command or configuration logic. Define how commands are configured and how the ten number keys invoke external commands or the mentioned pause/restart functions, then verify each key during both Pomodoro and break states.

Written by the indexing model from the issue text.