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>

deploy/antispam/docker-compose.antispam.yml

@@ -24,6 +24,10 @@ services:
       - antispam
 
   antispam:
+    # The milter: rspamd 3.11.1, conf/worker-proxy.inc, "milter = yes" for the
+    # rspamd_proxy worker, which the image binds to *:11332 (rspamd-docker
+    # v3.11.1+3, patches/rspamd-docker-config.diff), and runs as uid 11333
+    # (its Dockerfile, USER 11333:11333).
     image: rspamd/rspamd:3.11
     restart: unless-stopped
     # No host ports: only SelfPost talks to the milter on the compose network.