entrypoint: no link followed at the DMARC maps (audit I2)

Security audit 2026-10-17, finding I2 (= M4), stage 0. drop_links listed
the outbound maps, sasldb2, the key tree and mail.log but not the three
DMARC maps that postfix-config.sh creates as root with `[ -e ] || : >`
when DMARC_REPORTS_ENABLE=true; -e is false for a dangling link and the
redirect follows it, and /data/postfix is the panel's. Now the three are in
drop_links, and both map loops refuse to create through a link
(`[ -e ] || [ -L ] || : >`).

e2e: TestStartsOnA28Data plants a dangling /data/postfix/dmarc_transport
with DMARC reports on and expects the "removing the symbolic link" line,
no file at the link's target, and a regular map. To be run on the server
with the stage.

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

CHANGELOG.md

@@ -13,6 +13,9 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); version
   check. Adding a user, setting a password, changing an e-mail or a role on
   the user form, and deleting a user now ask for your own account password,
   as a backup does, under the same limit on wrong guesses.
+- **The entrypoint follows no link at the DMARC maps** (audit I2): the
+  three `dmarc_*` maps root creates at the start were missing from the list
+  of paths where a symbolic link is removed first.
 
 ## [2.14.3] - 2026-10-17