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/regenerator-runtime/README.md

@@ -0,0 +1,31 @@
+# regenerator-runtime
+
+Standalone runtime for
+[Regenerator](https://github.com/facebook/regenerator)-compiled generator
+and `async` functions.
+
+To import the runtime as a module (recommended), either of the following
+import styles will work:
+```js
+// CommonJS
+const regeneratorRuntime = require("regenerator-runtime");
+
+// ECMAScript 2015
+import regeneratorRuntime from "regenerator-runtime";
+```
+
+To ensure that `regeneratorRuntime` is defined globally, either of the
+following styles will work:
+```js
+// CommonJS
+require("regenerator-runtime/runtime");
+
+// ECMAScript 2015
+import "regenerator-runtime/runtime.js";
+```
+
+To get the absolute file system path of `runtime.js`, evaluate the
+following expression:
+```js
+require("regenerator-runtime/path").path
+```