feat(system-tray): add optional monochrome icons setting (#2241)

Adds a 'Monochrome Icons' toggle to the system tray widget context menu.
When enabled, all system tray icons are desaturated using MultiEffect,
giving a cleaner monochrome bar aesthetic that matches minimal themes.

The setting is per-user (settings.json), defaults to false to preserve
existing behavior.

quickshell/Common/SettingsData.qml

@@ -211,6 +211,7 @@ Singleton {
     property int selectedGpuIndex: 0
     property var enabledGpuPciIds: []
     property bool showSystemTray: true
+    property bool systemTrayMonochromeIcons: false
     property bool showClock: true
     property bool showNotificationButton: true
     property bool showBattery: true

quickshell/Common/settings/SettingsSpec.js

@@ -79,6 +79,7 @@ var SPEC = {
     selectedGpuIndex: { def: 0 },
     enabledGpuPciIds: { def: [] },
     showSystemTray: { def: true },
+    systemTrayMonochromeIcons: { def: false },
     showClock: { def: true },
     showNotificationButton: { def: true },
     showBattery: { def: true },

quickshell/Modules/DankBar/Widgets/SystemTrayBar.qml

@@ -366,6 +366,10 @@ BasePill {
                             smooth: true
                             mipmap: true
                             visible: status === Image.Ready
+                            layer.enabled: SettingsData.systemTrayMonochromeIcons
+                            layer.effect: MultiEffect {
+                                saturation: -1
+                            }
                         }
 
                         Text {
@@ -581,6 +585,10 @@ BasePill {
                     smooth: true
                     mipmap: true
                     visible: status === Image.Ready
+                    layer.enabled: SettingsData.systemTrayMonochromeIcons
+                    layer.effect: MultiEffect {
+                        saturation: -1
+                    }
                 }
 
                 Text {
@@ -709,6 +717,10 @@ BasePill {
                     smooth: true
                     mipmap: true
                     visible: status === Image.Ready
+                    layer.enabled: SettingsData.systemTrayMonochromeIcons
+                    layer.effect: MultiEffect {
+                        saturation: -1
+                    }
                 }
 
                 Text {
@@ -1210,6 +1222,10 @@ BasePill {
                             smooth: true
                             mipmap: true
                             visible: status === Image.Ready
+                            layer.enabled: SettingsData.systemTrayMonochromeIcons
+                            layer.effect: MultiEffect {
+                                saturation: -1
+                            }
                         }
 
                         Text {

quickshell/Modules/Settings/DankBarTab.qml

@@ -714,6 +714,15 @@ Item {
                     })
             }
 
+            SettingsToggleCard {
+                iconName: "filter_b_and_w"
+                title: I18n.tr("Monochrome System Tray Icons")
+                description: I18n.tr("Desaturate all system tray icons for a uniform monochrome look")
+                visible: selectedBarConfig?.enabled
+                checked: SettingsData.systemTrayMonochromeIcons
+                onToggled: checked => SettingsData.set("systemTrayMonochromeIcons", checked)
+            }
+
             SettingsToggleCard {
                 iconName: "mouse"
                 title: I18n.tr("Scroll Wheel")