fix(audio): route scaleAudioUrl through mediaBase — was hardcoded /media (404 on static)

The audio layer built the soundtrack url as a literal /media/audio/<f>, which 404s
on the static R2 build (audio err 4, silent). Route it through mediaBase() like the
video path: dev → /media/ (unchanged), static → https://static.benstull.art/. Verified
live: aud loads 200 from R2 and plays.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

simulator/static/app.js

@@ -1192,7 +1192,10 @@ function scaleAudioUrl(index) {
   if (!ring || !ring.scales.length) return null;
   const s = ring.scales[HEFScrub.wrapIndex(index, ring.scales.length)];
   const a = s.audio || SCALE_AUDIO_FALLBACK[s.id];
-  return a ? "/media/audio/" + a : null;
+  // Route through mediaBase() so audio loads from R2 in the static build (and the
+  // local /media mount in dev) — NOT a hardcoded /media path, which 404s on the
+  // static site. mediaUrl() then passes this absolute url straight through.
+  return a ? mediaBase() + "audio/" + a : null;
 }
 // The current resting altitude's soundtrack url (kept for the status readout).
 function soundtrackUrl() { return scaleAudioUrl(ringIndex); }