added customizable taskbar colors

[abanksss]

Pull Request

Motivation

Adds color customization to the taskbar buttons, needed because current version forces the hover color for focused windows and transparent backgrounds for unfocused windows.

Type of Change

Mark the relevant option with an "x".

• Bug fix
• New feature
• Breaking change
• Refactoring

Related Issue

• Closes Color Options for Taskbar Widget #2548

Testing

Describe how you tested your changes and mark the relevant items.

• Tested on niri
• Tested on Hyprland
• Tested on sway
• Tested with different bar positions and density settings
• Tested at different interface scaling values
• Tested with multiple monitors (if applicable)

Screenshots / Videos

If applicable, include screenshots or videos to help illustrate your changes.

Checklist

• Code follows project style guidelines
• Self-reviewed my code
• No new warnings or errors
• Documentation or comments updated (if relevant)

Additional Notes

Add any additional context or follow-up notes for reviewers.

• This is my first pull request so let me know if I should change anything
• Settings do not persist after restarting
• New settings labels and descriptions are hard coded in English
• Received the following warnings:

WARN scene: qs:/nix/store/zny9d3nw2hfnbsl4awd8swvq2681h932-noctalia-shell-2026-04-24_f6d3fc8/share/noctalia-shell/Modules/Bar/Widgets/Taskbar.qml[53:3]: Unable to assign [undefined] to QString
WARN scene: qs:/nix/store/zny9d3nw2hfnbsl4awd8swvq2681h932-noctalia-shell-2026-04-24_f6d3fc8/share/noctalia-shell/Modules/Panels/Settings/Bar/WidgetSettings/TaskbarSettings.qml[32:3]: Unable to assign [undefined] to QString