Podcast transcripts

[bcomnes]

It would be nice to build out transcript support. Apple generates these on public podcasts, so we can't use that feature, but we can re-expose existing transcripts and create our own for personal use.

• Capture and archive transcripts on episodes if already available.
• Test out redirect to existing transcripts, if available via the RSS tags
• Eventually: breadcrum generated transcripts on downloaded medai
• https://help.apple.com/itc/podcasts_connect/#/itcb54353390 (see transcripts tag)
• https://github.com/Podcastindex-org/podcast-namespace