port 25 ends DATA only at CRLF.CRLF: smtpd_forbid_bare_newline=normalize (port25-bare-newline)

Postfix 3.7.11 leaves its 2023 SMTP-smuggling defence off (default "no"
before 3.9, src/smtpd/smtpd.c:807), and the inbound relay's smtp/inet
listener did not turn it on: a "." line ended by a bare LF ended DATA and
what followed was read as the next transaction. The listener now sets
normalize (bare_lf_mask_table, smtpd.c:1656; the DATA loop drops such a
"." line, 3649-3652), the setting Postfix recommends and 3.9's default.
The submission ports keep the default (own-mta-builds, section 5).

Tests: e2e inbound_bare_newline_is_one_message sends the smuggling
sequence over raw SMTP (net/smtp's DotWriter would rewrite the bare LF)
and finds one message at the upstream with the smuggled part inside;
port25 config check asserts the parameter on smtp/inet. On the server:
make e2e exit 0 (511 s), go vet + go test 27 packages ok.

Docs: CHANGELOG [Unreleased] Security, security.md, architecture.md,
guide.md; roadmap: port25-bare-newline, base-trixie and
panel-dkim-signing agreed by the owner in this order.

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

docs/architecture.md

@@ -189,6 +189,11 @@ smtp/inet` removes Debian's stock smtpd). Outbound delivery still uses the
   panel's sender check (§ Panel roles).
 - **Level-1 rate limit** — `smtpd_client_message_rate_limit` /
   `anvil_rate_time_unit` from `RATE_LIMIT_*` env vars; independent of milter.
+- **Port 25 ends DATA only at `<CR><LF>.<CR><LF>`** —
+  `smtpd_forbid_bare_newline=normalize` on the `smtp/inet` listener (Postfix
+  3.7.11, `src/smtpd/smtpd.c`, the DATA loop at 3649: a `.` line next to a
+  bare `<LF>` is dropped, not taken as the end); a bare `<LF>` elsewhere is
+  read as `<CR><LF>`. The submission ports keep Postfix's default.
 - **Chroot disabled** for all services (DNS/TLS inside container).
 - **TLS certs** — read-only mount at `TLS_CERT_FILE` / `TLS_KEY_FILE`, copied
   at start into `/etc/postfix/tls-internal`, owned by root and `0600` as