feat(lotus-audio-inject): one soundboard clip at a time (replace mode)

playInjectedClip now stops any in-flight clip (via the existing idempotent
cleanup) before starting a new one, so rapid taps replace rather than
overlap/stack — no track leak. The host also debounces the button.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/lotus/lotusAudioInject.ts

@@ -101,6 +101,13 @@ async function playInjectedClip(
     return;
   }
 
+  // Max ONE clip at a time (replace mode): stop any in-flight clip before
+  // starting a new one, so clips can't overlap or be spammed. Runs
+  // synchronously before the first await, and each cleanup() is idempotent and
+  // removes itself from activeClips (so no track leak). The host also debounces
+  // the button; together they cover the brief fetch window.
+  for (const abort of [...activeClips]) abort();
+
   const resp = await fetch(url, { credentials: "omit", mode: "cors" });
   if (!resp.ok) throw new Error(`fetch ${url} -> ${resp.status}`);
   const arrayBuffer = await resp.arrayBuffer();