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/serialization/SingleItemMiddleware.js

@@ -0,0 +1,34 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+*/
+
+"use strict";
+
+const SerializerMiddleware = require("./SerializerMiddleware");
+
+/**
+ * @typedef {any} DeserializedType
+ * @typedef {any[]} SerializedType
+ * @extends {SerializerMiddleware<any, any[]>}
+ */
+class SingleItemMiddleware extends SerializerMiddleware {
+	/**
+	 * @param {DeserializedType} data data
+	 * @param {object} context context object
+	 * @returns {SerializedType|Promise<SerializedType>} serialized data
+	 */
+	serialize(data, context) {
+		return [data];
+	}
+
+	/**
+	 * @param {SerializedType} data data
+	 * @param {object} context context object
+	 * @returns {DeserializedType|Promise<DeserializedType>} deserialized data
+	 */
+	deserialize(data, context) {
+		return data[0];
+	}
+}
+
+module.exports = SingleItemMiddleware;