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/import-fresh/index.d.ts

@@ -0,0 +1,30 @@
+/**
+Import a module while bypassing the cache.
+
+@example
+```
+// foo.js
+let i = 0;
+module.exports = () => ++i;
+
+// index.js
+import importFresh = require('import-fresh');
+
+require('./foo')();
+//=> 1
+
+require('./foo')();
+//=> 2
+
+importFresh('./foo')();
+//=> 1
+
+importFresh('./foo')();
+//=> 1
+
+const foo = importFresh<typeof import('./foo')>('./foo');
+```
+*/
+declare function importFresh<T>(moduleId: string): T;
+
+export = importFresh;