Fix silent chime: reuse one AudioContext, unlocked on first user gesture

Toast now works (confirmed after the event-bus fix), but the sound never
played. Cause: a fresh AudioContext created outside a real user gesture
(click/keypress) starts in "suspended" state per browser autoplay
policy — an SSE message arriving is a network callback, not a gesture,
so every chime was silently creating a context that never actually
produced sound (start()/stop() don't throw on a suspended context, so
nothing surfaced this in testing without watching for it specifically).
Now a single AudioContext is created once and reused, resumed on the
page's first pointerdown/keydown — after that one real interaction it
stays running for the rest of the session, so every subsequent chime
actually plays.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012o9j9RezxbZVKQMrB7oRLY

src/app/(admin)/ticket-toasts.tsx

@@ -14,12 +14,37 @@ interface Toast {
   href: string;
 }
 
+// A single, reused AudioContext — created fresh per chime, an AudioContext
+// starts "suspended" unless made/resumed inside a real user gesture (click,
+// keypress, ...), and a chime triggered by an incoming SSE message is a
+// network callback, not a gesture. It fails *silently*: start()/stop() don't
+// throw, nothing plays. Reusing one context that's unlocked by the page's
+// first real click/keydown avoids that — once resumed, it stays running for
+// the rest of the session.
+let sharedAudioContext: AudioContext | null = null;
+
+function getAudioContext(): AudioContext | null {
+  if (typeof window === "undefined") return null;
+  const AudioCtor = window.AudioContext ?? (window as unknown as { webkitAudioContext?: typeof AudioContext }).webkitAudioContext;
+  if (!AudioCtor) return null;
+  if (!sharedAudioContext) sharedAudioContext = new AudioCtor();
+  return sharedAudioContext;
+}
+
+if (typeof window !== "undefined") {
+  const unlockAudio = () => {
+    getAudioContext()?.resume();
+  };
+  window.addEventListener("pointerdown", unlockAudio, { once: true });
+  window.addEventListener("keydown", unlockAudio, { once: true });
+}
+
 /** A short two-tone chime via the Web Audio API — no audio asset needed. */
 function playChime() {
+  const ctx = getAudioContext();
+  if (!ctx) return;
   try {
-    const AudioCtor = window.AudioContext ?? (window as unknown as { webkitAudioContext?: typeof AudioContext }).webkitAudioContext;
-    if (!AudioCtor) return;
-    const ctx = new AudioCtor();
+    if (ctx.state === "suspended") ctx.resume();
     const now = ctx.currentTime;
     for (const [freq, start] of [[880, 0], [1175, 0.12]] as const) {
       const osc = ctx.createOscillator();
@@ -34,7 +59,6 @@ function playChime() {
       osc.start(now + start);
       osc.stop(now + start + 0.25);
     }
-    setTimeout(() => ctx.close(), 500);
   } catch {
     // audio isn't critical to the notification — a silent toast still works
   }