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/@jsonjoy.com/fs-fsa/README.md

@@ -0,0 +1,35 @@
+# @jsonjoy.com/fs-fsa
+
+File System Access API implementation backed by `@jsonjoy.com/fs-core` primitives.
+
+Provides a [File System Access API](https://developer.mozilla.org/en-US/docs/Web/API/File_System_API)
+implementation that works with the `Superblock` filesystem abstraction.
+
+## Installation
+
+```bash
+npm install @jsonjoy.com/fs-fsa
+```
+
+## Usage
+
+```ts
+import { fsa } from '@jsonjoy.com/fs-fsa';
+
+const { dir, core, FileSystemObserver } = fsa({ mode: 'readwrite' });
+
+// Create a file
+const fileHandle = await dir.getFileHandle('hello.txt', { create: true });
+const writable = await fileHandle.createWritable();
+await writable.write('Hello, World!');
+await writable.close();
+
+// Read a file
+const file = await fileHandle.getFile();
+const contents = await file.text();
+console.log(contents); // 'Hello, World!'
+```
+
+## License
+
+Apache-2.0