Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/workbox-expiration/models/CacheTimestampsModel.d.ts

@@ -0,0 +1,77 @@
+import '../_version.js';
+/**
+ * Returns the timestamp model.
+ *
+ * @private
+ */
+declare class CacheTimestampsModel {
+    private readonly _cacheName;
+    private _db;
+    /**
+     *
+     * @param {string} cacheName
+     *
+     * @private
+     */
+    constructor(cacheName: string);
+    /**
+     * Performs an upgrade of indexedDB.
+     *
+     * @param {IDBPDatabase<CacheDbSchema>} db
+     *
+     * @private
+     */
+    private _upgradeDb;
+    /**
+     * Performs an upgrade of indexedDB and deletes deprecated DBs.
+     *
+     * @param {IDBPDatabase<CacheDbSchema>} db
+     *
+     * @private
+     */
+    private _upgradeDbAndDeleteOldDbs;
+    /**
+     * @param {string} url
+     * @param {number} timestamp
+     *
+     * @private
+     */
+    setTimestamp(url: string, timestamp: number): Promise<void>;
+    /**
+     * Returns the timestamp stored for a given URL.
+     *
+     * @param {string} url
+     * @return {number | undefined}
+     *
+     * @private
+     */
+    getTimestamp(url: string): Promise<number | undefined>;
+    /**
+     * Iterates through all the entries in the object store (from newest to
+     * oldest) and removes entries once either `maxCount` is reached or the
+     * entry's timestamp is less than `minTimestamp`.
+     *
+     * @param {number} minTimestamp
+     * @param {number} maxCount
+     * @return {Array<string>}
+     *
+     * @private
+     */
+    expireEntries(minTimestamp: number, maxCount?: number): Promise<string[]>;
+    /**
+     * Takes a URL and returns an ID that will be unique in the object store.
+     *
+     * @param {string} url
+     * @return {string}
+     *
+     * @private
+     */
+    private _getId;
+    /**
+     * Returns an open connection to the database.
+     *
+     * @private
+     */
+    private getDb;
+}
+export { CacheTimestampsModel };