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/graceful-fs/clone.js

@@ -0,0 +1,23 @@
+'use strict'
+
+module.exports = clone
+
+var getPrototypeOf = Object.getPrototypeOf || function (obj) {
+  return obj.__proto__
+}
+
+function clone (obj) {
+  if (obj === null || typeof obj !== 'object')
+    return obj
+
+  if (obj instanceof Object)
+    var copy = { __proto__: getPrototypeOf(obj) }
+  else
+    var copy = Object.create(null)
+
+  Object.getOwnPropertyNames(obj).forEach(function (key) {
+    Object.defineProperty(copy, key, Object.getOwnPropertyDescriptor(obj, key))
+  })
+
+  return copy
+}