Voice announcements run entirely in the Android foreground service
(works with screen locked). Configurable via web UI before starting
GPS: time-based or distance-based intervals, selectable metrics
(total time, distance, avg/split/current pace), language (en/de).
Also syncs workout pause/resume state to the native service — pausing
the workout timer now freezes the Android-side elapsed time, distance
accumulation, and TTS triggers.
Includes TTS engine detection with install prompt if none found, and
Android 11+ package visibility query for TTS service discovery.