Draft.js is a framework for building rich text editors. However, it does not support exporting documents at HTML. This gem is designed to take the raw `ContentState` (output of `convertToRaw`) from Draft.js and convert it to HTML using Ruby. This is a Zero One fork of the `draftjs_exporter` gem, published separately as `zo_draftjs_exporter`. It adds a `block_callback:` hook invoked after each block is rendered, and support for `className` entries in the `style_map` so inline styles can emit CSS classes alongside inline `style` attributes. It keeps the upstream `draftjs_exporter` require paths and `DraftjsExporter` namespace, so it cannot be installed alongside the original gem.