Replaces the gotoolkit helpers with the standard library and the
libraries they wrapped:
- gotoolkit/encoding TOML wrapper -> pelletier/go-toml/v2 directly,
behind a new smtp2shoutrrr.LoadConfig shared by both commands.
- gotoolkit/service + gotoolkit/model.Server -> signal.NotifyContext
and a concrete *Server whose Start shuts the listener down
gracefully when its context is cancelled.
Also drops the unused ANONYMOUS SASL client from cmd/sendmail, bumps
alpine, golangci-lint and the CI actions, and adds coverage for config
loading and the server lifecycle.
Closes FMG-2
Co-authored-by: multica-agent <github@multica.ai>
Full-Stack Developer
8c12783e95