add base handler and refactor H

service_a/internal/domains/handlers.go

@@ -0,0 +1,16 @@
+package domains
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+type (
+	BaseHandler struct{}
+)
+
+func (bh *BaseHandler) ToJSON(w http.ResponseWriter, statusCode int, data any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(statusCode)
+	json.NewEncoder(w).Encode(data)
+}