Add ThemedSlider, change all Slider to ThemedSlider, add scaling to Display.qml, fix scaling for ToggleOption

Settings/Settings.qml

@@ -82,6 +82,7 @@ Singleton {
             property var barMonitors: [] // Array of monitor names to show the bar on
             property var dockMonitors: [] // Array of monitor names to show the dock on
             property var notificationMonitors: [] // Array of monitor names to show notifications on, "*" means all monitors
+            property var monitorScaleOverrides: {} // Map of monitor name -> scale override (e.g., 0.8..2.0). When set, Theme.scale() returns this value
         }
     }
 

Settings/Theme.qml

@@ -13,7 +13,16 @@ Singleton {
     
     // Automatic scaling based on screen width
     function scale(currentScreen) {
-        if (currentScreen.width != 0) {
+        // Per-monitor override from settings
+        try {
+            const overrides = Settings.settings.monitorScaleOverrides || {};
+            if (currentScreen && currentScreen.name && overrides[currentScreen.name] !== undefined) {
+                return overrides[currentScreen.name];
+            }
+        } catch (e) {
+            // ignore
+        }
+        if (currentScreen && currentScreen.width != 0) {
             var ratio = currentScreen.width / designScreenWidth;
             // Limit the final scale range between [0.8...2]
             return Math.max(0.8, Math.min(2.0, ratio));