New docs/credentials.md covers member git-account provisioning, the
notify-creds backfill command (flags + behavior), required env, and the
two SMTP paths — transactional AGENTBBS_SMTP_* (STARTTLS :587) vs. the
gateway loopback relay AGENTBBS_MAIL_SMTP_ADDR (:25 into Mailu),
clarifying why :25 is correct and that 465 (not "467") is implicit-TLS.
Cross-linked from README ops and docs/mail.md.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
