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/wheel-texts-en.example

@@ -9,5 +9,9 @@
     "soundboard.title": "Soundboard",
     "soundboard.empty": "No sounds available",
     "soundboard.lastplayed": "Played by %user%",
-    "soundboard.room.setting.desc": "Let people in this room play sound effects"
+    "soundboard.room.setting.desc": "Let people in this room play sound effects",
+    "radio.title": "Radio",
+    "radio.empty": "No stations",
+    "radio.error": "Couldn't load stations",
+    "radio.stop": "Stop"
 }