Submit IANA media-type registration for application/vnd.portableweb+zip

[omscse]

Register the MIME type application/vnd.portableweb+zip in the IANA vendor tree.

Why: Formal registration makes the type official, improves interoperability, and is a prerequisite for broad ecosystem adoption (OS file associations, HTTP servers, CDNs).

Process:

1. Write registration template per RFC 6838 (vendor tree)
2. Submit via IANA media type review: https://www.iana.org/form/media-types
3. Address any reviewer feedback
4. Once registered, update spec docs and CLI/viewer to reference the official registration

Key fields:

• Type name: application/vnd.portableweb+zip
• Required parameters: none
• Encoding considerations: binary (ZIP)
• Published spec: portableweb.org/spec