feat: Realtime API support reboot (#5392)

* feat(realtime): Initial Realtime API implementation

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* chore: go mod tidy

Signed-off-by: Richard Palethorpe <io@richiejp.com>

* feat: Implement transcription only mode for realtime API

Reduce the scope of the real time API for the initial realease and make
transcription only mode functional.

Signed-off-by: Richard Palethorpe <io@richiejp.com>

* chore(build): Build backends on a separate layer to speed up core only changes

Signed-off-by: Richard Palethorpe <io@richiejp.com>

---------

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Signed-off-by: Richard Palethorpe <io@richiejp.com>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>

backend/backend.proto

@@ -162,6 +162,7 @@ message Reply {
   int32 prompt_tokens = 3;
   double timing_prompt_processing = 4;
   double timing_token_generation = 5;
+  bytes audio = 6;
 }
 
 message GrammarTrigger {

backend/go/vad/silero/vad.go

@@ -21,8 +21,8 @@ func (vad *VAD) Load(opts *pb.ModelOptions) error {
 		SampleRate: 16000,
 		//WindowSize:           1024,
 		Threshold:            0.5,
-		MinSilenceDurationMs: 0,
-		SpeechPadMs:          0,
+		MinSilenceDurationMs: 100,
+		SpeechPadMs:          30,
 	})
 	if err != nil {
 		return fmt.Errorf("create silero detector: %w", err)
@@ -35,6 +35,10 @@ func (vad *VAD) Load(opts *pb.ModelOptions) error {
 func (vad *VAD) VAD(req *pb.VADRequest) (pb.VADResponse, error) {
 	audio := req.Audio
 
+	if err := vad.detector.Reset(); err != nil {
+		return pb.VADResponse{}, fmt.Errorf("reset: %w", err)
+	}
+
 	segments, err := vad.detector.Detect(audio)
 	if err != nil {
 		return pb.VADResponse{}, fmt.Errorf("detect: %w", err)