feat(tui): show voice activity with green color and speaker icon when users talk

cmd/tui/main.go

@@ -48,6 +48,9 @@ func main() {
 	// Create Bubble Tea program
 	p := tea.NewProgram(m, tea.WithAltScreen())
 
+	// Pass program reference to model for event handlers
+	m.SetProgram(p)
+
 	// Set up log capture
 	r, w, _ := os.Pipe()
 	if debugFile != nil {