phosphor-surfaces

Higher-level surface manager on top of phosphor-layer. Given a SurfaceConfig, SurfaceManager warms up a QML scene synchronously and rejects async QML load paths, so callers must pass qrc:/ or file:/ URLs that resolve without a network hop. It creates the layer-shell window, wires in a caller-owned or library-managed QVulkanInstance, and hands back a Surface*. This is what app code actually instantiates when it needs a zone overlay, a drag ghost, or any layer-shell QML scene.