docs: stage 2b of the audit - the log tailer, refusals, the Sender check card

architecture.md
- § Log tailer: the fingerprint carries the inode; a log rotated while the
  panel was down is read from mail.log.1 to its end, or the gap is logged;
  a refusal's line (the queue id of a From: refusal, the NOQUEUE line put on
  a MAIL FROM refusal's row) and the refusal written from mail.log when the
  panel had not.
- § Sender check, what it costs: supervisord asked for half a minute, then
  the estimate and ≈; connections and messages in two columns; the count's
  saved place in the log.

guide.md
- § Outbound log: a refused message's page shows Postfix's line(s); rows
  from before, and a row written from mail.log, say so.
- § Overview and Health: the two columns and ≈.

schema-migrations row 9 was written with the migration. Audit plan line
ticked: stage 2b's lines are all done. Roadmap 30/62.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/audit-2026-10-12.md

@@ -834,7 +834,7 @@ order - each stands on the one before.
    M13 fix on, not yet deployed when this was decided. The mockup `health`
    and help topic `sender-check` first (`design:` commit), then the page and
    `view/help.go`, word for word. - **Sonnet**
-- [ ] Docs: architecture § Log tailer (the rotated file, the saved place, a
+- [x] Docs: architecture § Log tailer (the rotated file, the saved place, a
    refusal's line and a recovered row), guide § Outbound log and § Health,
    schema-migrations.md for the mark on `sender_check_days`. — **Sonnet**