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/detect-libc/index.d.ts

@@ -0,0 +1,14 @@
+// Copyright 2017 Lovell Fuller and others.
+// SPDX-License-Identifier: Apache-2.0
+
+export const GLIBC: 'glibc';
+export const MUSL: 'musl';
+
+export function family(): Promise<string | null>;
+export function familySync(): string | null;
+
+export function isNonGlibcLinux(): Promise<boolean>;
+export function isNonGlibcLinuxSync(): boolean;
+
+export function version(): Promise<string | null>;
+export function versionSync(): string | null;