One-page GitHub Pages site that forwards every wiki.vdbx.io URL to the same path on vdbx.io, where the wiki lives now. Namecheap's own URL redirect only answers over plain HTTP, and every link out there is HTTPS, so this repo exists to hold the certificate.
404.html does the work: any path on a Pages site that has no file lands on it, and the script forwards the browser with the path, query, and hash intact. index.html covers the root.