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/paths.js

@@ -0,0 +1,17 @@
+"use strict";
+/**
+ * @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
+ */
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.relativePathToWorkspaceRoot = relativePathToWorkspaceRoot;
+const posix_1 = require("node:path/posix");
+function relativePathToWorkspaceRoot(projectRoot) {
+    if (!projectRoot) {
+        return '.';
+    }
+    return (0, posix_1.relative)((0, posix_1.join)('/', projectRoot), '/') || '.';
+}