refactor: enhance UI components and improve theme properties for better visual consistency

src/pygui/ISC/Tabs/components/ReadoutPanel.qml

@@ -9,6 +9,39 @@ ColumnLayout {
     property alias showLabels: labelsToggle.checked
     property alias heatmapBlend: heatmapSlider.value
 
+    component PanelCheckBox: CheckBox {
+        id: toggle
+        indicator: Rectangle {
+            implicitWidth: 18
+            implicitHeight: 18
+            x: toggle.leftPadding
+            y: parent.height / 2 - height / 2
+            radius: Theme.radiusXs
+            color: toggle.checked ? Theme.primaryAccent : "transparent"
+            border.width: Theme.borderThin
+            border.color: toggle.checked ? Theme.primaryAccent : Theme.fieldBorder
+
+            Text {
+                anchors.centerIn: parent
+                text: "✓"
+                font.pixelSize: 13
+                font.bold: true
+                color: Theme.panelBackground
+                visible: toggle.checked
+                verticalAlignment: Text.AlignVCenter
+                horizontalAlignment: Text.AlignHCenter
+            }
+        }
+
+        contentItem: Text {
+            text: toggle.text
+            color: Theme.headingColor
+            verticalAlignment: Text.AlignVCenter
+            leftPadding: toggle.indicator.width + toggle.spacing
+            font.pixelSize: toggle.font.pixelSize || 11
+        }
+    }
+
     // ── READOUT ───────────────────────────────────────────────────────────
     Label {
         text: "READOUT"
@@ -142,7 +175,7 @@ ColumnLayout {
         bottomPadding: 8
     }
 
-    CheckBox {
+    PanelCheckBox {
         id: labelsToggle
         text: "Labels"
         checked: true
@@ -236,7 +269,7 @@ ColumnLayout {
 
     Item { height: 10 }
 
-    CheckBox {
+    PanelCheckBox {
         id: autoCheck
         text: "Auto range  (mean ± 1σ)"
         checked: true