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/adjust-sourcemap-loader/index.js

@@ -0,0 +1,10 @@
+/*
+ * MIT License http://opensource.org/licenses/MIT
+ * Author: Ben Holloway @bholloway
+ */
+'use strict';
+
+module.exports = Object.assign(require('./lib/loader'), {
+  moduleFilenameTemplate: require('./lib/module-filename-template'),
+  codec                 : require('./codec')
+});