add api response helper

internal/api/handlers/helpers.go

@@ -0,0 +1,12 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+func respond(w http.ResponseWriter, status int, data any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(data)
+}