feat: play sound for pending tool requests

Reuse the existing notification tone when a chat run pauses for actionable
tool approval.

Track pending permission state inside the realtime handler so the sound plays
when approval first becomes pending, including subscribe recovery, without
replaying for inline plan prompts or duplicate websocket events.

src/components/chat/view/ChatInterface.tsx

@@ -239,6 +239,7 @@ function ChatInterface({
     selectedSession,
     currentSessionId,
     setTokenBudget,
+    pendingPermissionRequests,
     setPendingPermissionRequests,
     streamTimerRef,
     accumulatedStreamRef,