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-filename/README.md

@@ -0,0 +1,34 @@
+unique-filename
+===============
+
+Generate a unique filename for use in temporary directories or caches.
+
+```js
+const uniqueFilename = require('unique-filename')
+
+// returns something like: '/tmp/c5b28f47'
+const randomTmpfile = uniqueFilename(os.tmpdir())
+
+// returns something like: '/tmp/my-test-51a7b48d'
+const randomPrefixedTmpfile = uniqueFilename(os.tmpdir(), 'my-test')
+
+// returns something like: '/my-tmp-dir/testing-7ddd44c0'
+const uniqueTmpfile = uniqueFilename('/my-tmp-dir', 'testing', '/my/thing/to/uniq/on')
+```
+
+### uniqueFilename(*dir*, *fileprefix*, *uniqstr*) → String
+
+Returns the full path of a unique filename that looks like:
+`dir/prefix-7ddd44c0`
+or `dir/7ddd44c0`
+
+*dir* – The path you want the filename in. `os.tmpdir()` is a good choice for this.
+
+*fileprefix* – A string to append prior to the unique part of the filename.
+The parameter is required if *uniqstr* is also passed in but is otherwise
+optional and can be `undefined`/`null`/`''`. If present and not empty
+then this string plus a hyphen are prepended to the unique part.
+
+*uniqstr* – Optional, if not passed the unique part of the resulting
+filename will be random.  If passed in it will be generated from this string
+in a reproducible way.