[Feature Request] Add WordPerfect (.wpd) support via the existing Tika/Gotenberg pipeline

Summary WordPerfect documents can't be consumed today, but everything needed to handle them is already running in a standard Tika-enabled deployment. The only missing piece is registering the MIME type, plus one extra workaround, described below. I've implemented and tested this as a third-party parser plugin against Paperless-ngx 3.0.5, verified end to end on two unrelated real WordPerfect documents. Happy to open a PR if you'd like it in core. Why this is nearly free • PDF rendition: Gotenberg's LibreOffice route already accepts .wpd — it's on the hardcoded extension allowlist in pkg/modules/libreoffice/api/api.go, and the Gotenberg image ships Debian's libreoffice-writer, which contains the WordPerfect import filter (libwpftwriterlo.so). • Text extraction: Tika ships org.apache.tika.parser.wordperfect.WordPerfectParser. • Detection: libmagic already identifies these files as application/vnd.wordperfec…