feat: migrate from msgpack to protobuf (handler-base v1.0.0)

- Replace msgpack encoding with protobuf wire format
- Update field names to proto convention (SessionId)
- Cast int fields to int32 (ChunkIndex, TotalChunks, SampleRate, Count)
- Use pointer slices for repeated messages ([]*TTSVoiceInfo)
- Rewrite tests for proto round-trips

main.go

@@ -18,7 +18,7 @@ import (
 	"time"
 
 	"github.com/nats-io/nats.go"
-	"github.com/vmihailenco/msgpack/v5"
+	"google.golang.org/protobuf/proto"
 
 	"git.daviestechlabs.io/daviestechlabs/handler-base/config"
 	"git.daviestechlabs.io/daviestechlabs/handler-base/health"
@@ -128,12 +128,12 @@ func (vr *VoiceRegistry) get(name string) *CustomVoice {
 	return vr.voices[name]
 }
 
-func (vr *VoiceRegistry) listVoices() []messages.TTSVoiceInfo {
+func (vr *VoiceRegistry) listVoices() []*messages.TTSVoiceInfo {
 	vr.mu.RLock()
 	defer vr.mu.RUnlock()
-	result := make([]messages.TTSVoiceInfo, 0, len(vr.voices))
+	result := make([]*messages.TTSVoiceInfo, 0, len(vr.voices))
 	for _, v := range vr.voices {
-		result = append(result, messages.TTSVoiceInfo{
+		result = append(result, &messages.TTSVoiceInfo{
 			Name:      v.Name,
 			Language:  v.Language,
 			ModelType: v.ModelType,
@@ -223,7 +223,7 @@ func main() {
 	// Helper: publish status
 	publishStatus := func(sessionID, status, message string) {
 		statusMsg := &messages.TTSStatus{
-			SessionID: sessionID,
+			SessionId: sessionID,
 			Status:    status,
 			Message:   message,
 			Timestamp: time.Now().Unix(),
@@ -285,13 +285,13 @@ func main() {
 			isLast := end >= len(audioBytes)
 
 			msg := &messages.TTSAudioChunk{
-				SessionID:   sessionID,
-				ChunkIndex:  chunkIndex,
-				TotalChunks: totalChunks,
+				SessionId:   sessionID,
+				ChunkIndex:  int32(chunkIndex),
+				TotalChunks: int32(totalChunks),
 				Audio:       chunk,
 				IsLast:      isLast,
 				Timestamp:   time.Now().Unix(),
-				SampleRate:  sampleRate,
+				SampleRate:  int32(sampleRate),
 			}
 			_ = nc.Publish(fmt.Sprintf("%s.%s", audioSubjectPrefix, sessionID), msg)
 		}
@@ -307,8 +307,8 @@ func main() {
 		}
 		sessionID := parts[4]
 
-		req, err := natsutil.Decode[messages.TTSRequest](natMsg.Data)
-		if err != nil {
+		var req messages.TTSRequest
+		if err := natsutil.Decode(natMsg.Data, &req); err != nil {
 			slog.Error("decode error", "error", err)
 			return
 		}
@@ -343,10 +343,10 @@ func main() {
 			streamAudio(sessionID, audioBytes)
 		} else {
 			msg := &messages.TTSFullResponse{
-				SessionID:  sessionID,
+				SessionId:  sessionID,
 				Audio:      audioBytes,
 				Timestamp:  time.Now().Unix(),
-				SampleRate: sampleRate,
+				SampleRate: int32(sampleRate),
 			}
 			_ = nc.Publish(fmt.Sprintf("%s.%s", audioSubjectPrefix, sessionID), msg)
 		}
@@ -368,7 +368,7 @@ func main() {
 			LastRefresh:    registry.lastRefresh.Unix(),
 			Timestamp:      time.Now().Unix(),
 		}
-		packed, _ := msgpack.Marshal(resp)
+		packed, _ := proto.Marshal(resp)
 		if msg.Reply != "" {
 			_ = msg.Respond(packed)
 		}
@@ -380,11 +380,11 @@ func main() {
 	if _, err := nc.Conn().Subscribe(voicesRefreshSubject, func(msg *nats.Msg) {
 		count := registry.refresh()
 		resp := &messages.TTSVoiceRefreshResponse{
-			Count:        count,
+			Count:        int32(count),
 			CustomVoices: registry.listVoices(),
 			Timestamp:    time.Now().Unix(),
 		}
-		packed, _ := msgpack.Marshal(resp)
+		packed, _ := proto.Marshal(resp)
 		if msg.Reply != "" {
 			_ = msg.Respond(packed)
 		}