feat: better caching headers for images

internal/handlers/restimage/resource.go

@@ -9,12 +9,15 @@ import (
 )
 
 type Handler struct {
+	http.Handler
 	img imageService
 }
 
-func New(mux *http.ServeMux, srv imageService) *Handler {
+func New(srv imageService) *Handler {
+	mux := http.NewServeMux()
 	h := &Handler{
-		img: srv,
+		Handler: mux,
+		img:     srv,
 	}
 
 	mux.HandleFunc("GET /images/{uid}", h.getImage)