voice: pre-route quiet-hours toggle, whisper ctx cancellation, stale reply fix

- resolveQuietToggle runs in HandlePushToTalk before the router so
  'тихий режим' works regardless of classifier confidence.
- whisper_full() runs in a goroutine with ctx.Done() select so the
  handler returns promptly on timeout/shutdown.
- StubReplier.IntentQuery no longer claims query is unimplemented.

cmd/mavsttd/whisper_handler.go

@@ -34,6 +34,9 @@ func newWhisperHandler(modelPath string) (*whisperHandler, error) {
 }
 
 func (h *whisperHandler) Transcribe(ctx context.Context, req worker.TranscribeReq) (worker.TranscribeResp, error) {
+	if err := ctx.Err(); err != nil {
+		return worker.TranscribeResp{}, fmt.Errorf("whisper: context done before transcribe: %w", err)
+	}
 	a := req.Audio
 	if len(a.Bytes) == 0 {
 		return worker.TranscribeResp{}, fmt.Errorf("whisper: empty audio")
@@ -59,10 +62,25 @@ func (h *whisperHandler) Transcribe(ctx context.Context, req worker.TranscribeRe
 	params.language = lang
 	params.detect_language = false
 
+	// CGo blocks the goroutine; whisper has no portable CGo-friendly abort
+	// callback. Run in a goroutine so the caller's context cancellation at
+	// least returns promptly — the CGo goroutine leaks until whisper finishes
+	// but the caller doesn't hang.
+	type result struct {
+		code int
+	}
+	ch := make(chan result, 1)
 	cSamples := (*C.float)(unsafe.Pointer(&samples[0]))
-	res := C.whisper_full(h.ctx, params, cSamples, C.int(nSamples))
-	if res != 0 {
-		return worker.TranscribeResp{}, fmt.Errorf("whisper: full failed: %d", int(res))
+	go func() {
+		ch <- result{code: int(C.whisper_full(h.ctx, params, cSamples, C.int(nSamples)))}
+	}()
+	select {
+	case r := <-ch:
+		if r.code != 0 {
+			return worker.TranscribeResp{}, fmt.Errorf("whisper: full failed: %d", r.code)
+		}
+	case <-ctx.Done():
+		return worker.TranscribeResp{}, fmt.Errorf("whisper: %w", ctx.Err())
 	}
 
 	nSegments := int(C.whisper_full_n_segments(h.ctx))