Add dhub cms

[vrepsys]

[!NOTE] Add Dhub CMS project page with metadata, images, and content describing features and framework support.

• Content:
  • Add content/projects/dhub.md with frontmatter (title, homepage, twitter, opensource, typeofcms, supportedgenerators, description, images).
  • Include sections detailing how Dhub works, key benefits, and framework support (Docusaurus, Next.js/React via Prose UI, general Markdown).

^{Written by Cursor Bugbot for commit 2cd1c691bec17d9e66a9e6508f49196040000e2a. This will update automatically on new commits. Configure here.}