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

e2e_test.go

@@ -13,7 +13,7 @@ import (
 
 	"git.daviestechlabs.io/daviestechlabs/handler-base/clients"
 	"git.daviestechlabs.io/daviestechlabs/handler-base/messages"
-	"github.com/vmihailenco/msgpack/v5"
+	"google.golang.org/protobuf/proto"
 )
 
 // ────────────────────────────────────────────────────────────────────────────
@@ -167,33 +167,33 @@ func TestChatPipeline_LLMTimeout(t *testing.T) {
 }
 
 func TestChatPipeline_TypedDecoding(t *testing.T) {
-	// Verify typed struct decoding from msgpack (same path as OnTypedMessage).
-	raw := map[string]any{
-		"request_id":       "req-e2e-001",
-		"user_id":          "user-1",
-		"message":          "hello",
-		"premium":          true,
-		"enable_rag":       false,
-		"enable_streaming": false,
-		"system_prompt":    "Be brief.",
+	// Verify typed struct decoding from proto (same path as OnTypedMessage).
+	original := &messages.ChatRequest{
+		RequestId:      "req-e2e-001",
+		UserId:         "user-1",
+		Message:        "hello",
+		Premium:        true,
+		EnableRag:      false,
+		EnableStreaming: false,
+		SystemPrompt:   "Be brief.",
 	}
-	data, _ := msgpack.Marshal(raw)
+	data, _ := proto.Marshal(original)
 
 	var req messages.ChatRequest
-	if err := msgpack.Unmarshal(data, &req); err != nil {
+	if err := proto.Unmarshal(data, &req); err != nil {
 		t.Fatal(err)
 	}
 
-	if req.RequestID != "req-e2e-001" {
-		t.Errorf("RequestID = %q", req.RequestID)
+	if req.RequestId != "req-e2e-001" {
+		t.Errorf("RequestID = %q", req.RequestId)
 	}
-	if req.UserID != "user-1" {
-		t.Errorf("UserID = %q", req.UserID)
+	if req.UserId != "user-1" {
+		t.Errorf("UserID = %q", req.UserId)
 	}
-	if req.EffectiveQuery() != "hello" {
-		t.Errorf("query = %q", req.EffectiveQuery())
+	if messages.EffectiveQuery(&req) != "hello" {
+		t.Errorf("query = %q", messages.EffectiveQuery(&req))
 	}
-	if req.EnableRAG {
+	if req.EnableRag {
 		t.Error("EnableRAG should be false")
 	}
 	if req.SystemPrompt != "Be brief." {