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/@parcel/watcher/scripts/build-from-source.js

@@ -0,0 +1,13 @@
+#!/usr/bin/env node
+
+const {spawn} = require('child_process');
+
+if (process.env.npm_config_build_from_source === 'true') {
+  build();
+}
+
+function build() {
+  spawn('node-gyp', ['rebuild'], { stdio: 'inherit', shell: true }).on('exit', function (code) {
+    process.exit(code);
+  });
+}