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/escalade/dist/index.mjs

@@ -0,0 +1,22 @@
+import { dirname, resolve } from 'path';
+import { readdir, stat } from 'fs';
+import { promisify } from 'util';
+
+const toStats = promisify(stat);
+const toRead = promisify(readdir);
+
+export default async function (start, callback) {
+	let dir = resolve('.', start);
+	let tmp, stats = await toStats(dir);
+
+	if (!stats.isDirectory()) {
+		dir = dirname(dir);
+	}
+
+	while (true) {
+		tmp = await callback(dir, await toRead(dir));
+		if (tmp) return resolve(dir, tmp);
+		dir = dirname(tmp = dir);
+		if (tmp === dir) break;
+	}
+}