milter, postfix, app, domain: cite the source of what they rely on (assumptions part B)

Comments only, no behaviour changed. go-milter v0.4.1 (session.go: one
session per connection, replaced after a non-continue reply; macros per
stage), Postfix 3.7.11 (milter8.c, smtpd_check.c
reject_auth_sender_login_mismatch(), mail_addr_find.c, showq_compat.c,
mail_conf_time.c, mail_params.h), Cyrus SASL 2.1.28 (saslpasswd.c,
plugins/sasldb.c: deleting a missing login is not an error), OpenDKIM
2.11.0~beta2 (opendkim-db.c, opendkim-genkey), Berkeley DB 5.3 db_dump,
rspamd 3.11.0. Comments that claimed what the source denies are corrected
(sasldb keeps the password as given, not hashed; an embedded newline is
kept, not truncated; rspamd sorts symbols by absolute weight); fixtures say
seen or composed. The sender check's From: parsing gets no citations: it is
replaced by the port of OpenDKIM's dkim_mail_parse next.

Contradictions left for their own commits: B-G5 cleanAddress, B-PS1 first
key wins, B-PQ1 the forced-expire flag, B-PQ10/PQ11 Postfix's time units.

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

internal/postfix/queuejson.go

@@ -12,6 +12,12 @@ import (
 
 // QueuedMessage is one message Postfix is holding, as `postqueue -j` reports
 // it: where it is, and since when.
+//
+// Postfix 3.7.11, src/postqueue/showq_json.c, format_json(): one object and a
+// newline per message - "queue_name", "queue_id", "arrival_time" (seconds,
+// %ld), "message_size", "forced_expire", "sender", "recipients" [{"address",
+// "delay_reason"}]; the queue names are those of src/global/mail_queue.h that
+// src/showq/showq.c, showq_service(), scans.
 type QueuedMessage struct {
 	ID         string
 	Queue      string // "deferred", "active", "hold", "incoming", "maildrop"