Downlink 2026-07-19

* https://go.dev/doc/tutorial/handle-errors * https://go.dev/doc/modules/layout#basic-command * https://go.dev/blog/package-names * https://go.dev/doc/tutorial/add-a-test * https://go.dev/blog/error-handling-and-go * https://pkg.go.dev/github.com/emersion/go-imap/v2/imapclient#example-Client * https://godocs.io/github.com/emersion/go-message/mail *…