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/zone.js/fesm2015/zone-patch-message-port.js

@@ -0,0 +1,20 @@
+'use strict';
+/**
+ * @license Angular v<unknown>
+ * (c) 2010-2025 Google LLC. https://angular.io/
+ * License: MIT
+ */
+function patchMessagePort(Zone) {
+    /**
+     * Monkey patch `MessagePort.prototype.onmessage` and `MessagePort.prototype.onmessageerror`
+     * properties to make the callback in the zone when the value are set.
+     */
+    Zone.__load_patch('MessagePort', (global, Zone, api) => {
+        const MessagePort = global['MessagePort'];
+        if (typeof MessagePort !== 'undefined' && MessagePort.prototype) {
+            api.patchOnProperties(MessagePort.prototype, ['message', 'messageerror']);
+        }
+    });
+}
+
+patchMessagePort(Zone);