Add floating traffic-light window chrome

Introduces a dedicated layer-shell `WindowChromeSurface` that renders macOS-style traffic-light controls over the focused Sway window titlebar, replacing the old top-bar window controls. Adds theme tokens and a reusable `TrafficLightButton` component, updates shell QML/CMake wiring, and adjusts Sway titlebar padding/title format so window titles do not overlap the overlay. Window tracking was extended with focused-window geometry/deco/fullscreen properties plus backend refresh support so the chrome follows window movement and state changes in near real time.

shells/desktop/shell/qml/components/TopBar.qml

@@ -23,7 +23,7 @@ Item {
         id: left
         anchors.left: parent.left
         anchors.leftMargin: 6
-        anchors.right: right.left
+        anchors.right: systemArea.left
         anchors.rightMargin: 12
         anchors.verticalCenter: parent.verticalCenter
         spacing: 8
@@ -54,28 +54,10 @@ Item {
         }
     }
 
-    Row {
-        id: right
+    SystemArea {
+        id: systemArea
         anchors.right: parent.right
         anchors.rightMargin: 10
         anchors.verticalCenter: parent.verticalCenter
-        spacing: windowControls.visible ? 8 : 0
-
-        WindowControls {
-            id: windowControls
-            anchors.verticalCenter: parent.verticalCenter
-        }
-
-        Rectangle {
-            visible: windowControls.visible
-            width: visible ? 1 : 0
-            height: 14
-            color: Theme.borderStrong
-            anchors.verticalCenter: parent.verticalCenter
-        }
-
-        SystemArea {
-            anchors.verticalCenter: parent.verticalCenter
-        }
     }
 }