Sub-plan 5 of the audiobooks absorption. Ports the plugin's
podcastfeed.Refresher into internal/audiobooks/podcastfeed and
registers it as a 10-minute scheduled task in silo's task manager.
For each row in podcast_feeds (sub-plan 1 mig 140), the refresher:
- Fetches the RSS feed with a 30-second HTTP timeout
- Parses entries via gofeed (github.com/mmcdole/gofeed)
- UPSERTs new entries into episodes (joined to the podcast's
media_items row via podcast_feeds.media_item_id = series_id)
- Updates podcast_feeds.last_refreshed_at + last_refresh_error
Migration 144 adds podcast_guid and podcast_audio_url columns to
episodes, plus a partial unique index on (series_id, podcast_guid)
WHERE podcast_guid IS NOT NULL so the refresher can ON CONFLICT upsert
without touching non-podcast episode rows.
Enclosure file download is deferred; this stage upserts episode
metadata only. Existing content_ids are reused when a feed re-emits a
known guid so per-user progress rows stay bound to the same FK target.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
