`omp say` for a short single-segment clip printed `spoke` but produced no
sound on hosts where the first streaming backend (bundled ffmpeg without a
pulse/alsa output device) spawns then exits nonzero. The single pipe write
succeeds into the OS buffer before the backend dies, so the drain's
broken-pipe replay never fires, and `player.end()` sets `#inputClosed`
before the exit lands, so the early-exit handler short-circuits and never
advances to paplay/aplay. The end-of-stream cleanup awaited the exit but
ignored its code.
StreamingAudioPlayer now retains the utterance PCM and, when the streaming
backend exits nonzero, replays it through per-file playback so short clips
still reach the speakers. Added injectable backend/file-playback seams and a
regression test exercising the nonzero-exit, clean-exit, and no-backend
paths.
Fixes#5875
roboomp
06661566dd