feat: Implement Dank Launcher button on the Dock

- Configurable with custom icons/logos
- Respects light/dark theme
- Drag & Drop in place

quickshell/Common/settings/SettingsSpec.js

@@ -255,6 +255,13 @@ var SPEC = {
     dockBorderOpacity: { def: 1.0, coerce: percentToUnit },
     dockBorderThickness: { def: 1 },
     dockIsolateDisplays: { def: false },
+    dockLauncherEnabled: { def: false },
+    dockLauncherLogoMode: { def: "apps" },
+    dockLauncherLogoCustomPath: { def: "" },
+    dockLauncherLogoColorOverride: { def: "" },
+    dockLauncherLogoSizeOffset: { def: 0 },
+    dockLauncherLogoBrightness: { def: 0.5, coerce: percentToUnit },
+    dockLauncherLogoContrast: { def: 1, coerce: percentToUnit },
 
     notificationOverlayEnabled: { def: false },
     overviewRows: { def: 2, persist: false },