Fix deadlock on exit by making mic level updates async

pkg/audio/capture.go

@@ -22,6 +22,7 @@ type Capturer struct {
 	running       bool
 	mu            sync.Mutex
 	stopChan      chan struct{}
+	wg            sync.WaitGroup
 
 	// Callback for captured audio (called with 960-sample frames)
 	onAudio func(samples []int16)
@@ -136,6 +137,7 @@ func (c *Capturer) Start() error {
 		return fmt.Errorf("failed to start audio client: %w", err)
 	}
 
+	c.wg.Add(1)
 	go c.captureLoop()
 	return nil
 }
@@ -151,6 +153,7 @@ func (c *Capturer) Stop() {
 	c.mu.Unlock()
 
 	close(c.stopChan)
+	c.wg.Wait() // Wait for capture loop to finish before proceeding
 	c.client.Stop()
 }
 
@@ -180,6 +183,7 @@ func (c *Capturer) IsRunning() bool {
 }
 
 func (c *Capturer) captureLoop() {
+	defer c.wg.Done()
 	ticker := time.NewTicker(10 * time.Millisecond) // Check more often than 20ms
 	defer ticker.Stop()