Add quick toggles to the grab bar

Beside the gear: full keyboard, hold keys, and the numeric keypad,
navigation and function key sections, each behind a drawn icon and lit
while on. Section toggles hide when the layout lacks the section. The
grab pill narrows when a small window leaves it less room.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

qml/DragHandle.qml

@@ -5,13 +5,15 @@ import QtQuick
 Item {
     id: handle
 
+    // Narrower when the bar's buttons leave less room in the middle.
+    property real pillWidth: 120
     signal dragStarted()
 
     implicitHeight: 22
 
     Rectangle {
         anchors.centerIn: parent
-        width: 120
+        width: handle.pillWidth
         height: 5
         radius: height / 2
         color: Theme.handle