Fix: relay WebSocket messages as text frames (browsers got Blobs they could not parse)

Root cause of 'track does not start': the server re-broadcast incoming frames as
binary (Buffer), so the browser output page received Blobs, JSON.parse failed,
and every command (playTrack, etc.) was silently dropped — only the text-encoded
lastEffect sync got through. Broadcast as text now; net.js also handles Blob
defensively. Also: no-store for app assets + kiosk --disk-cache-size=1 so
redeploys always take effect; /api/clients debug endpoint; /api/peaks duration.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/kiosk.sh

@@ -11,4 +11,5 @@ exec "$BIN" \
   --ozone-platform=wayland \
   --ignore-gpu-blocklist \
   --test-type \
+  --disk-cache-size=1 --disable-back-forward-cache \
   "$URL" >/tmp/chromium-kiosk.log 2>&1