feat: add Tiptap JSON to HTML converter with advanced formatting support

- Implemented a web interface for converting Tiptap/ProseMirror JSON documents to HTML.
- Added support for various Tiptap-specific nodes and marks, including code blocks, task lists, and text alignment.
- Included features for formatting, validating, and clearing JSON input.
- Enabled auto-conversion of JSON input to HTML with a toggle button.
- Provided example documents for testing and demonstration purposes.
- Implemented functionality for copying, downloading, and printing the generated HTML.

Author: tacxou