키 관리 로직을 Keyring으로 통합하여 하드코딩된 MEK 및 HSK 버전을 제거하고 Svelte Store를 Rune으로 대체

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/lib/client/media/thumbnail.ts

@@ -1,5 +1,3 @@
-import { encodeToBase64 } from "#lib/shared/crypto/index.js";
-
 const scaleSize = (width: number, height: number, targetSize: number) => {
   if (width <= targetSize || height <= targetSize) {
     return { width, height };
@@ -116,7 +114,3 @@ export const generateThumbnail = async (blob: Blob) => {
     }
   }
 };
-
-export const getThumbnailUrl = (thumbnailBuffer: ArrayBuffer) => {
-  return `data:image/webp;base64,${encodeToBase64(thumbnailBuffer)}`;
-};