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.

core/windows/WindowBackend.hpp

@@ -38,6 +38,7 @@ public:
     virtual bool resizeWindow(qint64 windowId, int width, int height) = 0;
     virtual bool snapWindow(qint64 windowId, SnapEdge edge) = 0;
     virtual bool switchWorkspace(const QString &workspaceId) = 0;
+    virtual bool updateFocusedGeometry() { return false; }
 
 signals:
     void connectedChanged();