Added model and role translation. Rewrite of code's comments.

src/remoteimage.ts

@@ -1,3 +1,17 @@
+/**
+ * @fileoverview This file provides a utility function for fetching a remote
+ * image and encoding it in base64.
+ */
+
+/**
+ * Fetches an image from a URL and returns
+ * its MIME type and base64-encoded data.
+ *
+ * @param url - The URL of the image to fetch.
+ * @returns A promise that resolves to an object containing the MIME type and
+ *   base64-encoded image data.
+ * @throws Throws an error if the image fetch fails.
+ */
 export async function fetchAndEncode(url: string) {
   const res = await fetch(url);
   if (!res.ok) throw new Error(`Failed to fetch image: ${url}`);