build, deploy, inbound, dmarc, backup, e2e: cite the source of what they rely on (assumptions part C)

Comments only, no behaviour changed. Each main.cf/master.cf parameter the
build sets, the wrapper's and the reload hook's reliance on Postfix 3.7.11
(postfix-script, master.5, postconf.5, cleanup_init.c, smtpd_peer.c,
README_FILES), supervisor 4.2.5 (process.py, options.py, events.rst),
logrotate 3.21.0, OpenDKIM's config, Cyrus SASL's sasldb, rspamd 3.11.1
(milter_headers.lua, multimap, the map watcher), Docker Compose, CoreDNS
and certbot now say where that is written. Measurements already there stay
measurements ("date not recorded" where none was); hand-composed fixtures
say so.

Contradictions left for their own commits: C-P31 cleanup's size limit,
C-P42 master outside supervisor's signal, C-V5/V6 startsecs, C-V10,
C-S3/Q3 sasldb written in place, C-Q4/A1 certbot's symlinks, C-R7 rspamd
skips local clients but the signature routine does not, C-P8, C-R4, C-R12,
C-M7, C-E2, C-K8/K9, C-D1.

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

test/e2e/port25_config_check.go

@@ -33,7 +33,8 @@ type port25Case struct {
 // ingestService is the dmarc-ingest service as Postfix must read it back.
 // flags=, user= and argv= are arguments of pipe(8); set as -o parameters they
 // are dropped, and a bare "pipe" dies on every report with "fatal: missing
-// user= command-line attribute" - the state of 1.7.0 through 1.9.5.
+// user= command-line attribute" - the state of 1.7.0 through 1.9.5 (date not
+// recorded; Postfix 3.7.11, src/pipe/pipe.c, get_service_attr()).
 const ingestService = "dmarc-ingest unix - n n - 1 pipe flags=Rq user=panel argv=/usr/local/bin/dmarc-ingest ${recipient}"
 
 var port25Cases = []port25Case{
@@ -145,7 +146,9 @@ func checkPort25ConfigCombinations(s *stack) error {
 			// a service line on whitespace, so a value with a space in it is
 			// cut at the space and the rest becomes a stray smtpd argument
 			// ("fatal: unexpected command-line argument", port 25 dead while
-			// `postfix check` stays silent). Ask Postfix itself.
+			// `postfix check` stays silent). Ask Postfix itself. (Seen in 1.9.1,
+			// date not recorded; Postfix 3.7.11, man/man5/master.5, "-o
+			// name=value (short form)", NOTE 2.)
 			seen, err := s.execIn("selfpost", "postconf", "-Ph", "smtp/inet/"+c.param)
 			if err != nil {
 				return fmt.Errorf("%s: postconf -P smtp/inet/%s: %v\n%s", tc.name, c.param, err, seen)