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/@schematics/angular/utility/dependencies.d.ts

@@ -0,0 +1,23 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+import { Tree } from '@angular-devkit/schematics';
+export declare enum NodeDependencyType {
+    Default = "dependencies",
+    Dev = "devDependencies",
+    Peer = "peerDependencies",
+    Optional = "optionalDependencies"
+}
+export interface NodeDependency {
+    type: NodeDependencyType;
+    name: string;
+    version: string;
+    overwrite?: boolean;
+}
+export declare function addPackageJsonDependency(tree: Tree, dependency: NodeDependency, pkgJsonPath?: string): void;
+export declare function removePackageJsonDependency(tree: Tree, name: string, pkgJsonPath?: string): void;
+export declare function getPackageJsonDependency(tree: Tree, name: string, pkgJsonPath?: string): NodeDependency | null;