feat: support external and step images with structured cooking instructions

src/app/api/[...path]/route.ts

@@ -249,7 +249,10 @@ async function handle(req: Request, ctx: Context) {
         .parse(await jsonBody(req));
       if (
         (await listRecipes(true)).some(
-          (r) => r.image === `/media/${name}` || r.images.includes(`/media/${name}`),
+          (r) =>
+            r.image === `/media/${name}` ||
+            r.images.includes(`/media/${name}`) ||
+            r.steps.some((s) => s.images.includes(`/media/${name}`)),
         )
       )
         throw new ApiError(409, 'Das Bild wird noch von einem Rezept verwendet.');