audit 2c: the rest the sources contradict, and the documents

Code and config:
- C-M7: a DMARC report's explicit <pct>0</pct> stays 0; only an absent
  pct takes RFC 7489 § 6.3's default 100 (Pct *int).
- C-D1: docs/development.md now tables the Debian versions the citations
  were read at (postfix 3.7.11-0+deb12u1, opendkim and libopendkim11
  2.11.0~beta2-8+deb12u1, libmilter1.0.1 8.17.1.9-2+deb12u2, libsasl2-2 and
  sasl2-bin 2.1.28+dfsg-10, supervisor 4.2.5-1, logrotate 3.21.0-1 - read off
  the image with dpkg-query, 2026-10-15); the e2e stand's new
  checkCitedPackageVersions fails when the image it built differs.
- C-E2: the e2e zone's SOA serial only grows (CoreDNS v1.14.6's file
  plugin reloads on a grown serial, not on mtime); Corefile comment says
  so; TestZoneSerialGrows.
- C-K8, C-K9: the e2e compose and stage comments say how
  --project-directory and .env resolve.
- D-arch:154: postfix-config.sh's "Postfix insists" comment says what
  TLS_README advises and that smtpd reads the key as root.
- B-G7: inflight.go's reservationTTL comment: a dropped client does give
  ABORT (smtpd_proto() -> mail_reset() -> milter_abort()); the TTL is for
  smtpd dying or the milter connection breaking.
- D-guide:301: the nginx fragment's first-certificate command now reaches
  certbot (--entrypoint certbot, --standalone, port 80 free), and the
  renewal loop passes --webroot -w /var/www/certbot - a standalone
  certificate would otherwise renew standalone while nginx holds port 80
  (certbot docs, "Renewing certificates": the issuing plugin is used
  "unless you specify other plugins or options", and options of a
  successful renewal are saved). The register's proposal missed that.

Documents: every D-arch, D-guide and D-sec claim the register's Answers E
found false or partly true, rewritten - by three Sonnet agents, one per
document, then reviewed: two proposals were obsolete after this stage's
fixes and not used (a bounce's From: line - extract_from = "smtp" now;
"Origin: null" - Referrer-Policy is same-origin now); a stand
observation the agent had dated from a commit is now tied to the e2e test
that checks it; the SQLite writers paragraph describes _txlock=immediate;
the log tailer's rotation paragraph describes the minute's grace; the
guide's nginx steps were put in working order (links and modes before
`up`, no reconfigure step). "Deferred" is kept for Postfix's queue in the
guide too. guide.md's CRLF from the agent normalised.

Stand (2026-10-15, make e2e, exit 0, the version gate and zone serial
test included); go vet and go test ./... pass on the server (24 packages).

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

CHANGELOG.md

@@ -158,6 +158,22 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); version
   A full backup follows links under `certs/` and carries the files; a link
   that leads nowhere stops it, named (assumptions C-A1, C-Q4). If you use
   certbot this way, follow the guide's new "Reverse proxy" steps.
+- **A DMARC report with `pct=0` says 0.** An explicit `<pct>0</pct>` - a
+  policy applied to no message - was shown as 100, the value for a report
+  that leaves `pct` out (assumptions C-M7).
+- **The nginx fragment's first certificate is issued, and renewed.** The
+  command it gave passed its arguments to the renewal loop, which ignored
+  them, and used the webroot nginx could not serve yet. It is now
+  `run --entrypoint certbot ... --standalone` with port 80 free, and the
+  renewal loop names nginx's webroot, which a standalone certificate would
+  otherwise not use (assumptions D-guide:301).
+- **The guide, architecture and security documents say what the code
+  does.** Some forty claims the sources contradict, or only partly bear out,
+  are corrected: what the rate limits count, what a backup restore message
+  looks like, how to pass the backup password, what the queue and Health
+  show, a backup MX's preference, the DMARC report address, what the
+  password store keeps, what the delivery log holds, and others
+  (assumptions, Answers E).
 - **Words for what happens to mail match Postfix's.** A message refused with
   a temporary error while the panel or the spam filter does not answer was
   called deferred, which in Postfix's words is mail waiting in its queue;