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/unique-slug/README.md

@@ -0,0 +1,19 @@
+unique-slug
+===========
+
+Generate a unique character string suitible for use in files and URLs.
+
+```
+var uniqueSlug = require('unique-slug')
+
+var randomSlug = uniqueSlug()
+var fileSlug = uniqueSlug('/etc/passwd')
+```
+
+### uniqueSlug(*str*) → String (8 chars)
+
+If *str* is passed in then the return value will be its murmur hash in
+hex.
+
+If *str* is not passed in, it will be 4 randomly generated bytes
+converted into 8 hexadecimal characters.