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_test.go

@@ -11,7 +11,7 @@ import (
 
 	"git.daviestechlabs.io/daviestechlabs/handler-base/messages"
 	"git.daviestechlabs.io/daviestechlabs/handler-base/natsutil"
-	"github.com/vmihailenco/msgpack/v5"
+	"google.golang.org/protobuf/proto"
 )
 
 func TestVoiceRegistryRefresh(t *testing.T) {
@@ -105,18 +105,18 @@ func TestSynthesizeHTTP(t *testing.T) {
 }
 
 func TestTTSRequestDecode(t *testing.T) {
-	req := messages.TTSRequest{
+	req := &messages.TTSRequest{
 		Text:     "hello world",
 		Speaker:  "custom-en",
 		Language: "en",
 		Stream:   true,
 	}
-	data, err := msgpack.Marshal(&req)
+	data, err := proto.Marshal(req)
 	if err != nil {
 		t.Fatal(err)
 	}
-	decoded, err := natsutil.Decode[messages.TTSRequest](data)
-	if err != nil {
+	var decoded messages.TTSRequest
+	if err := natsutil.Decode(data, &decoded); err != nil {
 		t.Fatal(err)
 	}
 	if decoded.Text != "hello world" {
@@ -132,7 +132,7 @@ func TestTTSRequestDecode(t *testing.T) {
 
 func TestTTSAudioChunkRoundtrip(t *testing.T) {
 	chunk := messages.TTSAudioChunk{
-		SessionID:   "sess-001",
+		SessionId:   "sess-001",
 		ChunkIndex:  0,
 		TotalChunks: 2,
 		Audio:       make([]byte, 32768),
@@ -140,16 +140,16 @@ func TestTTSAudioChunkRoundtrip(t *testing.T) {
 		Timestamp:   1234567890,
 		SampleRate:  24000,
 	}
-	data, err := msgpack.Marshal(&chunk)
+	data, err := proto.Marshal(&chunk)
 	if err != nil {
 		t.Fatal(err)
 	}
 	var got messages.TTSAudioChunk
-	if err := msgpack.Unmarshal(data, &got); err != nil {
+	if err := proto.Unmarshal(data, &got); err != nil {
 		t.Fatal(err)
 	}
-	if got.SessionID != "sess-001" {
-		t.Errorf("SessionID = %q", got.SessionID)
+	if got.SessionId != "sess-001" {
+		t.Errorf("SessionID = %q", got.SessionId)
 	}
 	if len(got.Audio) != 32768 {
 		t.Errorf("Audio len = %d", len(got.Audio))