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/@npmcli/node-gyp/lib/index.js

@@ -0,0 +1,14 @@
+const util = require('util')
+const fs = require('fs')
+const { stat } = fs.promises || { stat: util.promisify(fs.stat) }
+
+async function isNodeGypPackage (path) {
+  return await stat(`${path}/binding.gyp`)
+    .then(st => st.isFile())
+    .catch(() => false)
+}
+
+module.exports = {
+  isNodeGypPackage,
+  defaultGypInstallScript: 'node-gyp rebuild',
+}