feat: hotel radio widget (client-side, multi-station)

Adds a compact collapsible radio widget (top-left) that plays internet
radio streams with the HTML5 Audio API — no server/renderer changes.

- station list loaded from a JSON5 config file (loadGamedata: JSON + JSON5),
  shipped as radio-stations.json5.example so each hotel fills in its own
- shows the selected station + a dropdown (3 visible, scrolls if more) to
  switch; volume slider; animated equalizer + LIVE indicator
- first station autostarts quietly (5%) on load, with a resume-on-first-
  gesture fallback for browser autoplay policy

public/configuration/radio-stations.json5.example

@@ -0,0 +1,19 @@
+{
+    // Hotel radio stations. Copy this file to `radio-stations.json5` (without the
+    // .example suffix) and add your own stations — each entry is just a streaming
+    // URL the client plays with the HTML5 Audio API. JSON5: // comments and
+    // trailing commas are allowed. Add / remove / reorder freely, no rebuild needed.
+    //
+    // Fields:
+    //   id    - unique key (string)
+    //   name  - label shown in the radio widget
+    //   genre - optional subtitle
+    //   url   - the audio stream URL (mp3/aac/ogg Icecast or Shoutcast)
+    //   logo  - optional image URL shown next to the station
+    //
+    // The first station autostarts (quietly) on client load. The list can later
+    // be moved to the CMS (website_settings) so it's editable from the admin.
+    stations: [
+        // { id: 'mystation', name: 'My Station', genre: 'Hotel Radio', url: 'https://your-stream-host/stream' },
+    ],
+}