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/is-wsl/readme.md

@@ -0,0 +1,21 @@
+# is-wsl
+
+> Check if the process is running inside [Windows Subsystem for Linux](https://msdn.microsoft.com/commandline/wsl/about) (Bash on Windows)
+
+Can be useful if you need to work around unimplemented or buggy features in WSL. Supports both WSL 1 and WSL 2.
+
+## Install
+
+```sh
+npm install is-wsl
+```
+
+## Usage
+
+```js
+import isWsl from 'is-wsl';
+
+// When running inside Windows Subsystem for Linux
+console.log(isWsl);
+//=> true
+```