fix(deprecations): remove dead ScriptProcessorNode PCM code (eliminates console warning); improve YouTube playerVars with origin/modestbranding (reduce postMessage spam); fix Timer stopwatch (now properly counts UP, clean display + interval)

Per PLAN item 7.

frontend/src/components/MusicPlayer.tsx

@@ -45,6 +45,8 @@ export default function MusicPlayer() {
           loop: 1,
           playlist: active.videoId,
           enablejsapi: 1,
+          origin: window.location.origin,
+          modestbranding: 1,
         },
         events: {
           onReady: (e: any) => {

frontend/src/components/Timer.tsx

@@ -68,6 +68,9 @@ export default function Timer() {
     if (!running) return;
     intervalRef.current = setInterval(() => {
       setRemaining((r) => {
+        if (mode === 'stopwatch') {
+          return r + 1;  // count UP for stopwatch
+        }
         if (r <= 1) {
           stop();
           if (mode === 'pomodoro') setSessions((s) => s + 1);
@@ -79,7 +82,7 @@ export default function Timer() {
     return stop;
   }, [running, mode, stop]);
 
-  const progress = presetMinutes > 0 ? 1 - remaining / (presetMinutes * 60) : 0;
+  const progress = mode === 'stopwatch' ? 0 : (presetMinutes > 0 ? 1 - remaining / (presetMinutes * 60) : 0);
 
   return (
     <div className="glass-card p-4">
@@ -112,10 +115,7 @@ export default function Timer() {
       {/* Timer display */}
       <div className="text-center py-2">
         <div className="text-5xl font-extrabold tracking-widest text-kira-plum tabular-nums">
-          {mode === 'stopwatch'
-            ? formatTime(Math.floor((presetMinutes * 60 - remaining + presetMinutes * 60) || remaining))
-            : formatTime(remaining)
-          }
+          {formatTime(remaining)}
         </div>
 
         {/* Progress bar */}

frontend/src/hooks/useConversation.ts

@@ -307,36 +307,4 @@ function arrayBufferToBase64(buffer: ArrayBufferLike): string {
   return btoa(binary);
 }
 
-/** Capture PCM16 mono 24kHz audio from mic and send via callback. */
-function startPCMCapture(
-  stream: MediaStream,
-  onChunk: (pcm16: Uint8Array) => void,
-): { stop: () => void } {
-  const ctx = new AudioContext({ sampleRate: 24000 });
-  const source = ctx.createMediaStreamSource(stream);
-  const processor = ctx.createScriptProcessor(4096, 1, 1);
-  let running = true;
-
-  processor.onaudioprocess = (e) => {
-    if (!running) return;
-    const input = e.inputBuffer.getChannelData(0);
-    const pcm16 = new Int16Array(input.length);
-    for (let i = 0; i < input.length; i++) {
-      const s = Math.max(-1, Math.min(1, input[i]));
-      pcm16[i] = s < 0 ? s * 0x8000 : s * 0x7fff;
-    }
-    onChunk(new Uint8Array(pcm16.buffer));
-  };
-
-  source.connect(processor);
-  processor.connect(ctx.destination);
-
-  return {
-    stop: () => {
-      running = false;
-      source.disconnect();
-      processor.disconnect();
-      ctx.close();
-    },
-  };
-}
+// (Legacy PCM capture removed - MediaRecorder full-blob path is active; eliminates ScriptProcessorNode deprecation)