Initial commit: notification-elements-demo app

Interactive Angular 19 demo for @sda/notification-elements-ui with
6 sections: Bell & Feed, Notification Center, Inbox, Comments &
Threads, Mention Input, and Full-Featured layout. Includes mock
data, dark mode toggle, and real-time event log.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

node_modules/webpack/lib/util/memoize.js

@@ -0,0 +1,33 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+*/
+
+"use strict";
+
+/** @template T @typedef {function(): T} FunctionReturning */
+
+/**
+ * @template T
+ * @param {FunctionReturning<T>} fn memorized function
+ * @returns {FunctionReturning<T>} new function
+ */
+const memoize = fn => {
+	let cache = false;
+	/** @type {T | undefined} */
+	let result;
+	return () => {
+		if (cache) {
+			return /** @type {T} */ (result);
+		}
+
+		result = fn();
+		cache = true;
+		// Allow to clean up memory for fn
+		// and all dependent resources
+		/** @type {FunctionReturning<T> | undefined} */
+		(fn) = undefined;
+		return /** @type {T} */ (result);
+	};
+};
+
+module.exports = memoize;