More flexible cursor movement

I love this project, thanks for doing this!

One thing I miss from Emacs is the flexibility in commands for moving the cursor. In gitu navigating the log history can feel quite slow at times. Would it be possible to make the navigation commands more diversified or flexible? E.g. move cursor 5 lines, move to top or bottom of screen, etc.

For reference yazi has a very flexible configuration scheme for this: https://yazi-rs.github.io/docs/configuration/keymap#manager.arrow

Argument/Option	Description
[steps]	The number of steps the cursor moves up or down.

[steps] can be one of the following values:

    n: Move the cursor n lines up or down, negative for up, positive for down.
    n%: Move the cursor n% of the screen height up or down, negative for up, positive for down.
    "top": Move the cursor to the first file.
    "bot": Move the cursor to the last file.

The issue names no file or test; start by tracing gitu’s log-history cursor navigation and command or key configuration. Done means navigation supports more flexible movement, including step counts and top or bottom destinations, with tests covering the new behavior.