Dock, Tray, ActiveWindow, Taskbar: add theming for app/tray icons

appicon_colorize: create simple shader to colorize icons by theme color

Modules/Bar/Widgets/Tray.qml

@@ -193,6 +193,14 @@ Rectangle {
           }
           opacity: status === Image.Ready ? 1 : 0
 
+          layer.enabled: widgetSettings.colorizeIcons !== false
+          layer.effect: ShaderEffect {
+            property color targetColor: Color.mOnSurface
+            property real colorizeMode: 1.0 // Tray mode (intensity-based)
+
+            fragmentShader: Qt.resolvedUrl(Quickshell.shellDir + "/Shaders/qsb/appicon_colorize.frag.qsb")
+          }
+
           MouseArea {
             anchors.fill: parent
             hoverEnabled: true