External feeds now explain why they're failing
GET /v1/external_feeds and GET /v1/external_feeds/{id} now return a read-only error string when a feed is failing. The field is null when the feed is reachable.
This covers cases like Cloudflare bot protection, SiteGround's captcha, a blocking robots.txt, and other fetch failures. See RSS-to-email for how to allowlist Buttondown's IP addresses.