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/autoprefixer/lib/hacks/animation.js

@@ -0,0 +1,17 @@
+let Declaration = require('../declaration')
+
+class Animation extends Declaration {
+  /**
+   * Don’t add prefixes for modern values.
+   */
+  check(decl) {
+    return !decl.value.split(/\s+/).some(i => {
+      let lower = i.toLowerCase()
+      return lower === 'reverse' || lower === 'alternate-reverse'
+    })
+  }
+}
+
+Animation.names = ['animation', 'animation-direction']
+
+module.exports = Animation