Add CKEditor-based rich document editor workflow

[beNative]

Summary

• add a CKEditor-backed rich text editor component with licensing setup and styling assets
• thread the new rich_text doc type through document creation, classification, repositories, exports, and UI rendering with a toolbar toggle between visual and source engines
• adjust preview/export behaviors and folder labeling to reflect the new editor engine while keeping Monaco available for source mode

Testing

• npm run test:markdown

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Codex Task