mavsttd: silence gate — don't feed non-speech to whisper

Whisper hallucinates subtitle-credit boilerplate ("Редактор субтитров …") on
silence/room-noise, which then got stored as tap:voice facts. Gate before the
model: drop clips shorter than -min-ms (default 300) or below -silence-rms
(default 0.01 normalized RMS). Both are flags — the mic floor is hardware
specific. Returns empty transcript (same as whisper's no-segments path), so
nothing downstream changes.

gateReason is pure and unit-tested (silence/short/quiet → dropped, loud+long →
passes). ponytail: energy gate, not a real VAD; upgrade to WebRTC VAD or
whisper no_speech_prob if too blunt.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cmd/mavsttd/main.go

@@ -47,6 +47,8 @@ func main() {
 func run(args []string) error {
 	sock := flag.String("socket", defaultSocket("stt.sock"), "unix socket path")
 	model := flag.String("model", "", "path to whisper ggml model file")
+	minMs := flag.Int("min-ms", 300, "drop clips shorter than this (silence gate); whisper hallucinates on short/quiet audio")
+	silenceRMS := flag.Float64("silence-rms", 0.01, "drop clips with normalized RMS below this (silence gate); tune to your mic floor")
 	flag.CommandLine.Parse(args)
 
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)
@@ -54,7 +56,7 @@ func run(args []string) error {
 
 	var t worker.Transcriber
 	if *model != "" {
-		w, err := newWhisperHandler(*model)
+		w, err := newWhisperHandler(*model, *minMs, *silenceRMS)
 		if err != nil {
 			return fmt.Errorf("whisper: %w", err)
 		}