By: Michael Lynch <git@mtlynch.io>
Keep encoded media content types independent of host MIME mappings Derive content types from the supported output formats instead of the host MIME database. A host can classify .webm as audio/webm, causing video publication to fail with "invalid content type: unsupported value "audio/webm"" despite producing a WebM video. Cover a conflicting host mapping, supported formats, case-insensitive extensions, and unsupported extensions through the storage API.