서버, 클라이언트, 서비스 워커 공용 코드를 lib/shared로 분리하고 브라우저 전용 모듈을 lib/client로 재구성

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

src/lib/client/storage/indexedDB/cacheIndex.ts

@@ -0,0 +1,33 @@
+import { Dexie, type EntityTable } from "dexie";
+
+export interface FileCacheIndex {
+  fileId: number;
+  cachedAt: Date;
+  lastRetrievedAt: Date;
+  size: number;
+}
+
+const cacheIndex = new Dexie("cacheIndex") as Dexie & {
+  fileCache: EntityTable<FileCacheIndex, "fileId">;
+};
+
+cacheIndex.version(1).stores({
+  fileCache: "fileId",
+});
+
+export const getFileCacheIndex = async () => {
+  return await cacheIndex.fileCache.toArray();
+};
+
+export const storeFileCacheIndex = async (fileCacheIndex: FileCacheIndex) => {
+  await cacheIndex.fileCache.put({
+    fileId: fileCacheIndex.fileId,
+    cachedAt: fileCacheIndex.cachedAt,
+    lastRetrievedAt: fileCacheIndex.lastRetrievedAt,
+    size: fileCacheIndex.size,
+  });
+};
+
+export const deleteFileCacheIndex = async (fileId: number) => {
+  await cacheIndex.fileCache.delete(fileId);
+};