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/compiler-cli/linker/index.d.ts

@@ -0,0 +1,15 @@
+/**
+ * @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
+ */
+export { AstHost, Range } from './src/ast/ast_host';
+export { assert } from './src/ast/utils';
+export { FatalLinkerError, isFatalLinkerError } from './src/fatal_linker_error';
+export { DeclarationScope } from './src/file_linker/declaration_scope';
+export { FileLinker } from './src/file_linker/file_linker';
+export { LinkerEnvironment } from './src/file_linker/linker_environment';
+export { DEFAULT_LINKER_OPTIONS, LinkerOptions } from './src/file_linker/linker_options';
+export { needsLinking } from './src/file_linker/needs_linking';