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/istanbul-lib-coverage/lib/percent.js

@@ -0,0 +1,15 @@
+/*
+ Copyright 2012-2015, Yahoo Inc.
+ Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
+ */
+'use strict';
+
+module.exports = function percent(covered, total) {
+    let tmp;
+    if (total > 0) {
+        tmp = (1000 * 100 * covered) / total;
+        return Math.floor(tmp / 10) / 100;
+    } else {
+        return 100.0;
+    }
+};