base-trixie: the image on Debian trixie, Postfix 3.10.13; Received: hidden on 465/587

The runtime base is debian:trixie-slim, the build stage golang:1.26-trixie:
Postfix 3.10.13 with upstream's 2026 security fixes up to the August
batch, libmilter 8.18.1, OpenSSL 3.5. Every citation of another program in
code, scripts and documents was re-read against the trixie sources
(dev/upstream; bookworm's kept in dev/upstream-bookworm) and updated;
development.md's cited-package table holds the trixie versions.

What the re-reading changed in behaviour:
- logtail: reject lines with sasl_method/sasl_username/sasl_sender
  (smtpd_check.c:1019-1026); cleanup's "removed (canceled)" forgets a
  port-25 id (cleanup_api.c:363-364).
- internal/postfix/retry.go reads postconf's stdout only: since 3.9 a
  deprecated-parameter warning on stderr made one value too many and the
  panel fell back to the compiled-in retry policy.
- logrotate-loop.sh: logrotate 3.22 exits 1 when it ignores a config;
  the loop refuses on that output whatever the status.
- postfix-config.sh: cyrus_sasl_config_path set explicitly (bookworm's
  07_sasl_config.diff is gone); maillog_file_permissions=0640; mynetworks
  explicit; Dockerfile: SYNC_CHROOT= in /etc/default/postfix,
  opendkim-tools dropped, openssl named, systemd-standalone-sysusers so
  cron does not bring the whole of systemd.
- The selfpost group is 10998, outside the system range 100-999: in
  trixie a package took 998 and the build failed (owner's decision:
  a conflict-free id, the distribution's own ids untouched). The
  entrypoint hands /data back by name when the user or the group differs.
  Guide, backup refusal text, help (design commit 68ec8b2), e2e.
- smtpd_hide_client_session=yes on smtps and submission (owner's
  decision): Received: names no client, TLS, login or protocol; port 25
  keeps the full header. e2e checks both.
- test/upstream/opendkim-probe.sh makes keys with openssl genrsa.

Tests: on the server, make e2e exit 0 (674 s, the image built on trixie),
go vet + go test 27 packages ok. CHANGELOG [Unreleased], guide,
architecture.md, security.md, roadmap.

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

cmd/panel/main.go

@@ -37,7 +37,7 @@ func main() {
 		log.SetPrefix("dmarc-ingest: ")
 		if err := runDMARCIngestMode(); err != nil {
 			log.Printf("ingest failed: %v", err)
-			// EX_TEMPFAIL — ask Postfix to defer. Postfix 3.7.11,
+			// EX_TEMPFAIL — ask Postfix to defer. Postfix 3.10.13,
 			// src/global/pipe_command.c, pipe_command(): a sysexits code maps
 			// to its DSN (src/global/sys_exits.c: 75 is "4.3.0") and a 4 defers,
 			// unless the output starts with a "D.S.N text" of its own - the
@@ -223,7 +223,7 @@ func antispamAction(raw string) string {
 
 // saslRealm chooses the realm new SASL accounts live under. It mirrors the
 // hostname Postfix's SASL layer uses so a client authenticating with a bare
-// login resolves to the right account. Postfix 3.7.11,
+// login resolves to the right account. Postfix 3.10.13,
 // src/xsasl/xsasl_cyrus_server.c, xsasl_cyrus_server_create(): serverFQDN is
 // $myhostname (= SELFPOST_HOSTNAME, build/postfix-config.sh) and user_realm
 // NULL while smtpd_sasl_local_domain is empty; Cyrus SASL 2.1.28,