feat(ui): render the Radio panel's directory, station card and transport from a store

RadioPanel, lifted from ContextView, renders the layer state, Enable, the tag filter, station card, transport, volume and playback line from the gev-radio store that RadioControls publishes to. The tuner, the local SDR card and the Cockpit radio controls keep their element bindings. Enable's busy mark and the dragged volume go through the owner so a render never leaves them stale, and the markup's tag option stands until the categories first change. ./ui/radio now imports Vue and Pinia.

docs/VUE-MIGRATION.md

@@ -102,7 +102,11 @@ They contain no application state.
    style parameter rows render through Vue behind `createStyleParameters()`,
    as a render function so the portable `./ui/input` entry needs no
    component compiler; the other groups follow one owner at a time),
-   Context and Radio, the command dock,
+   Context and Radio (in progress: `RadioPanel` renders the directory row,
+   station card, transport, volume and playback line from the `gev-radio`
+   store that RadioControls publishes to; the tuner, the local SDR card and
+   the Cockpit radio controls keep their owners' element bindings), the
+   command dock,
    the phone shell, then Cockpit. Layers that write into the right rail
    directly gain a slot instead.