Episode search results gain d (download), D (delete), x (unsubscribe)
and enter (play for subscribed shows); downloads of unsubscribed shows
are recorded with the show's metadata under a deterministic synthetic
feed id and listed under an "Unsubscribed Show Downloads" section in
My Shows and the settings Download Manager. Classified at render time
by feed id or feed URL, so subscribing re-classifies the downloads and
unsubscribing purges them.
- mpv: --force-media-title '<podcast> — <episode>' so macOS Now Playing shows
the podcast name instead of the download-hash filename (mediaTitle PlayOption)
- media registry: artist is now the human podcast title (customName ||
podcast.title), falling back to podcastId
- downloads: write the podcast cover as a <base>.jpg sibling so mpv's
cover-art-auto=exact picks it up for artwork; delete it with the download
