v9

What's new in this version:

• Option to check a command's output to determine button state at startup.
• Option to check a command's exit code and toggle button state only if command executes successfully (returns exit code 0).
• Added feature to export current button configurations to a file.
• Fixed a compatibility issue with some systems (such as NixOS) by switching from /bin/bash to /usr/bin/env bash for command execution.
• Added support for GNOME 48.
• Minor UI improvements.
• Improved code readability.