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/@pkgjs/parseargs/internal/util.js

@@ -0,0 +1,14 @@
+'use strict';
+
+// This is a placeholder for util.js in node.js land.
+
+const {
+  ObjectCreate,
+  ObjectFreeze,
+} = require('./primordials');
+
+const kEmptyObject = ObjectFreeze(ObjectCreate(null));
+
+module.exports = {
+  kEmptyObject,
+};