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/@angular/platform-browser/testing/index.d.ts

@@ -0,0 +1,29 @@
+/**
+ * @license Angular v19.2.18
+ * (c) 2010-2025 Google LLC. https://angular.io/
+ * License: MIT
+ */
+
+import * as i0 from '@angular/core';
+import { StaticProvider, PlatformRef } from '@angular/core';
+import { BrowserModule } from '../browser.d-CXj5swf3.js';
+import '@angular/common';
+
+/**
+ * Platform for testing
+ *
+ * @publicApi
+ */
+declare const platformBrowserTesting: (extraProviders?: StaticProvider[]) => PlatformRef;
+/**
+ * NgModule for testing.
+ *
+ * @publicApi
+ */
+declare class BrowserTestingModule {
+    static ɵfac: i0.ɵɵFactoryDeclaration<BrowserTestingModule, never>;
+    static ɵmod: i0.ɵɵNgModuleDeclaration<BrowserTestingModule, never, never, [typeof BrowserModule]>;
+    static ɵinj: i0.ɵɵInjectorDeclaration<BrowserTestingModule>;
+}
+
+export { BrowserTestingModule, platformBrowserTesting };