Make the hideDeadPodcasts sync with Podcast Index operation merge with existing podcasts if available #756
Description
This work is blocked until we replace the user.subscribedPodcastIds JSON column with a join table.
If the killed feed is marked as a duplicate of another feed, the second column will contain the PI feed id that is the correct one so you can move the subscriptions to it.
https://podcastindex.social/@dave/111608975384589866
replaces podverse/podverse-workers#1 bug