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

- Replace msgpack encoding with protobuf wire format
- Update field names to proto convention
- Use pointer slices for repeated message fields ([]*DocumentSource)
- Rewrite tests for proto round-trips

main.go

@@ -16,6 +16,7 @@ import (
 	"git.daviestechlabs.io/daviestechlabs/handler-base/handler"
 	"git.daviestechlabs.io/daviestechlabs/handler-base/messages"
 	"git.daviestechlabs.io/daviestechlabs/handler-base/natsutil"
+	"google.golang.org/protobuf/proto"
 )
 
 func main() {
@@ -43,13 +44,13 @@ func main() {
 
 	h := handler.New("voice.request", cfg)
 
-	h.OnTypedMessage(func(ctx context.Context, msg *nats.Msg) (any, error) {
-		req, err := natsutil.Decode[messages.VoiceRequest](msg.Data)
-		if err != nil {
+	h.OnTypedMessage(func(ctx context.Context, msg *nats.Msg) (proto.Message, error) {
+		var req messages.VoiceRequest
+		if err := natsutil.Decode(msg.Data, &req); err != nil {
 			return &messages.VoiceResponse{Error: "Invalid request encoding"}, nil
 		}
 
-		requestID := req.RequestID
+		requestID := req.RequestId
 		if requestID == "" {
 			requestID = "unknown"
 		}
@@ -64,8 +65,8 @@ func main() {
 
 		slog.Info("processing voice request", "request_id", requestID)
 
-		errResp := func(msg string) (any, error) {
-			return &messages.VoiceResponse{RequestID: requestID, Error: msg}, nil
+		errResp := func(msg string) (proto.Message, error) {
+			return &messages.VoiceResponse{RequestId: requestID, Error: msg}, nil
 		}
 
 		// 1. Audio arrives as raw bytes — no base64 decode needed
@@ -146,7 +147,7 @@ func main() {
 
 		// Build typed response
 		result := &messages.VoiceResponse{
-			RequestID: requestID,
+			RequestId: requestID,
 			Response:  responseText,
 			Audio:     responseAudio,
 		}
@@ -160,13 +161,13 @@ func main() {
 			if len(documents) < limit {
 				limit = len(documents)
 			}
-			result.Sources = make([]messages.DocumentSource, limit)
+			result.Sources = make([]*messages.DocumentSource, limit)
 			for i := 0; i < limit; i++ {
 				text := documents[i].Document
 				if len(text) > 200 {
 					text = text[:200]
 				}
-				result.Sources[i] = messages.DocumentSource{Text: text, Score: documents[i].Score}
+				result.Sources[i] = &messages.DocumentSource{Text: text, Score: documents[i].Score}
 			}
 		}