Try fixing bad live transcription performance.

src/lib/mic.ts

@@ -131,7 +131,7 @@ export async function startMicCapture(
     audio: { echoCancellation: true, noiseSuppression: true, autoGainControl: true },
   });
 
-  const context = new AudioContext();
+  const context = new AudioContext({ sampleRate: TARGET_SAMPLE_RATE });
   // Contexts created outside a user gesture start suspended; the start button
   // click satisfies the gesture requirement, so this resolves immediately.
   await context.resume().catch(() => {});