Applescript that responds to key presses?
The easiest way of accomplishing this is probably to use Automator to create a Service. The service should just execute your a bash script similar to this:

#!/bin/bash
ddcctl -d 1 -b 10


Then in System Preference under Keyboard, add a keyboard shortcut to activate your Service.

This way your shortcut will work across all programs.

You'll probably need to do this for each of the 10 keyboard shortcuts you need.