feat(ui): render the Cockpit utility launchers and compact Radio controls from a store

The Display and Radio launchers, their popovers and the compact Radio
transport, Enable button and volume now render from the Radio store.
RadioControls owns the disclosure state; Cockpit Escape and the Display
reveal read that state instead of the DOM, and the Enable toggle guards
re-presses synchronously. The compact transport reuses the panel's
transport state and adds only its glyph and title.

src/ui/radioControls.js

@@ -29,6 +29,7 @@ export class RadioControls {
     this._radioCategorySignature = '';
     this._radioFilterOptions = null;
     this._radioVolumeShown = null;
+    this._cockpitDisclosure = { display: false, radio: false };
     this._radioTunerStations = [];
     this._radioTunerPool = [];
     this._radioTunerDragging = false;