LauncherTab: check if app2unit exists

Modules/Settings/Tabs/LauncherTab.qml

@@ -95,8 +95,14 @@ ColumnLayout {
   NToggle {
     label: I18n.tr("settings.launcher.settings.use-app2unit.label")
     description: I18n.tr("settings.launcher.settings.use-app2unit.description")
-    checked: Settings.data.appLauncher.useApp2Unit
-    onToggled: checked => Settings.data.appLauncher.useApp2Unit = checked
+    checked: Settings.data.appLauncher.useApp2Unit && ProgramCheckerService.app2unitAvailable
+    enabled: ProgramCheckerService.app2unitAvailable
+    opacity: ProgramCheckerService.app2unitAvailable ? 1.0 : 0.6
+    onToggled: checked => {
+      if (ProgramCheckerService.app2unitAvailable) {
+        Settings.data.appLauncher.useApp2Unit = checked
+      }
+    }
   }
 
   NTextInput {

Services/ProgramCheckerService.qml

@@ -18,6 +18,7 @@ Singleton {
   property bool fuzzelAvailable: false
   property bool gpuScreenRecorderAvailable: false
   property bool wlsunsetAvailable: false
+  property bool app2unitAvailable: false
 
   // Discord client auto-detection
   property var availableDiscordClients: []
@@ -85,6 +86,7 @@ Singleton {
                                             "ghosttyAvailable": ["which", "ghostty"],
                                             "footAvailable": ["which", "foot"],
                                             "fuzzelAvailable": ["which", "fuzzel"],
+                                            "app2unitAvailable": ["which", "app2unit"],
                                             "gpuScreenRecorderAvailable": ["sh", "-c", "command -v gpu-screen-recorder >/dev/null 2>&1 || (command -v flatpak >/dev/null 2>&1 && flatpak list --app | grep -q 'com.dec05eba.gpu_screen_recorder')"],
                                             "wlsunsetAvailable": ["which", "wlsunset"]
                                           })