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/events/tests/symbols.js

@@ -0,0 +1,25 @@
+'use strict';
+
+var common = require('./common');
+var EventEmitter = require('../');
+var assert = require('assert');
+
+var ee = new EventEmitter();
+var foo = Symbol('foo');
+var listener = common.mustCall();
+
+ee.on(foo, listener);
+assert.strictEqual(ee.listeners(foo).length, 1);
+assert.strictEqual(ee.listeners(foo)[0], listener);
+
+ee.emit(foo);
+
+ee.removeAllListeners();
+assert.strictEqual(ee.listeners(foo).length, 0);
+
+ee.on(foo, listener);
+assert.strictEqual(ee.listeners(foo).length, 1);
+assert.strictEqual(ee.listeners(foo)[0], listener);
+
+ee.removeListener(foo, listener);
+assert.strictEqual(ee.listeners(foo).length, 0);