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/@babel/helper-create-class-features-plugin/README.md

@@ -0,0 +1,19 @@
+# @babel/helper-create-class-features-plugin
+
+> Compile class public and private fields, private methods and decorators to ES6
+
+See our website [@babel/helper-create-class-features-plugin](https://babeljs.io/docs/babel-helper-create-class-features-plugin) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save @babel/helper-create-class-features-plugin
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/helper-create-class-features-plugin
+```