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/sync/index.js

@@ -0,0 +1,18 @@
+const { dirname, resolve } = require('path');
+const { readdirSync, statSync } = require('fs');
+
+module.exports = function (start, callback) {
+	let dir = resolve('.', start);
+	let tmp, stats = statSync(dir);
+
+	if (!stats.isDirectory()) {
+		dir = dirname(dir);
+	}
+
+	while (true) {
+		tmp = callback(dir, readdirSync(dir));
+		if (tmp) return resolve(dir, tmp);
+		dir = dirname(tmp = dir);
+		if (tmp === dir) break;
+	}
+}