feat(map): add min/max highlighting toggle and live safeguards

- Add "Highlight Min/Max" option to ReadoutPanel showing peak rings.
- Reset to review mode and blank wafer map when switching away from map tab.
- Disable hover highlights and sensor dialog triggers during live stream.
- Lower trendPane height and add top margin headroom for tick labels.
- Add test coverage for blanking states, toggle overrides, and interactions.

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

@@ -12,6 +12,7 @@ ColumnLayout {
     spacing: 6
     property var s: streamController.stats
     property alias showLabels: labelsToggle.checked
+    property alias showExtremes: extremesToggle.checked
     property alias heatmapBlend: heatmapSlider.value
     property alias showThickness: thicknessToggle.checked
 
@@ -353,6 +354,13 @@ ColumnLayout {
                 font.pixelSize: Theme.fontSm
             }
 
+            PanelCheckBox {
+                id: extremesToggle
+                text: "Highlight Min/Max"
+                checked: true
+                font.pixelSize: Theme.fontSm
+            }
+
             PanelCheckBox {
                 id: clusterAverageToggle
                 text: "Average Clusters"

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

@@ -7,6 +7,7 @@ Item {
     id: root
     property real blend: 0.0
     property bool showLabels: true
+    property alias showExtremes: map.showExtremes
     property alias showThickness: map.showThickness
 
     WaferMapItem {
@@ -39,7 +40,9 @@ Item {
         HoverHandler {
             id: hoverHandler
             onPointChanged: {
-                map.hoveredIndex = map.which_marker(hoverHandler.point.position.x, hoverHandler.point.position.y);
+                map.hoveredIndex = streamController.mode === "live"
+                    ? -1
+                    : map.which_marker(hoverHandler.point.position.x, hoverHandler.point.position.y);
             }
             onHoveredChanged: if (!hoverHandler.hovered) map.hoveredIndex = -1
             cursorShape: map.hoveredIndex >= 0 ? Qt.PointingHandCursor : Qt.ArrowCursor
@@ -47,6 +50,8 @@ Item {
 
         TapHandler {
             onTapped: ev => {
+                if (streamController.mode === "live")
+                    return;
                 var idx = map.which_marker(ev.position.x, ev.position.y);
                 if (idx >= 0)
                     replaceDialog.openFor(idx);