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

- Replace msgpack encoding with protobuf wire format
- Update field names to proto convention (UserId, RequestId, EnableRag, etc.)
- Use messages.EffectiveQuery() standalone function
- Cast TopK to int32 for proto compatibility
- Rewrite tests for proto round-trips

main_test.go

@@ -5,28 +5,31 @@ import (
 	"testing"
 
 	"git.daviestechlabs.io/daviestechlabs/handler-base/messages"
-	"github.com/vmihailenco/msgpack/v5"
+	"google.golang.org/protobuf/proto"
 )
 
 func TestChatRequestDecode(t *testing.T) {
-	// Verify a msgpack-encoded map decodes cleanly into typed struct.
-	raw := map[string]any{
-		"request_id": "req-1",
-		"user_id":    "user-1",
-		"message":    "hello",
-		"premium":    true,
-		"top_k":      10,
+	// Verify a proto-encoded struct round-trips cleanly.
+	original := &messages.ChatRequest{
+		RequestId: "req-1",
+		UserId:    "user-1",
+		Message:   "hello",
+		Premium:   true,
+		TopK:      10,
 	}
-	data, _ := msgpack.Marshal(raw)
-	var req messages.ChatRequest
-	if err := msgpack.Unmarshal(data, &req); err != nil {
+	data, err := proto.Marshal(original)
+	if err != nil {
 		t.Fatal(err)
 	}
-	if req.RequestID != "req-1" {
-		t.Errorf("RequestID = %q", req.RequestID)
+	var req messages.ChatRequest
+	if err := proto.Unmarshal(data, &req); err != nil {
+		t.Fatal(err)
 	}
-	if req.EffectiveQuery() != "hello" {
-		t.Errorf("EffectiveQuery = %q", req.EffectiveQuery())
+	if req.RequestId != "req-1" {
+		t.Errorf("RequestID = %q", req.RequestId)
+	}
+	if messages.EffectiveQuery(&req) != "hello" {
+		t.Errorf("EffectiveQuery = %q", messages.EffectiveQuery(&req))
 	}
 	if !req.Premium {
 		t.Error("Premium should be true")
@@ -38,20 +41,20 @@ func TestChatRequestDecode(t *testing.T) {
 
 func TestChatResponseRoundtrip(t *testing.T) {
 	resp := &messages.ChatResponse{
-		UserID:   "user-1",
+		UserId:   "user-1",
 		Response: "answer",
 		Success:  true,
 		Audio:    []byte{0x01, 0x02, 0x03},
 	}
-	data, err := msgpack.Marshal(resp)
+	data, err := proto.Marshal(resp)
 	if err != nil {
 		t.Fatal(err)
 	}
 	var decoded messages.ChatResponse
-	if err := msgpack.Unmarshal(data, &decoded); err != nil {
+	if err := proto.Unmarshal(data, &decoded); err != nil {
 		t.Fatal(err)
 	}
-	if decoded.UserID != "user-1" || !decoded.Success {
+	if decoded.UserId != "user-1" || !decoded.Success {
 		t.Errorf("decoded = %+v", decoded)
 	}
 	if len(decoded.Audio) != 3 {