logtail: deliveryRe anchored at the head of the line (audit M12)

The pattern that writes a row's status matched anywhere in a line: a
port-25 reject line ending helo=<ID: to=<victim@...>, status=sent> parsed
as (ID, victim, sent). parseDelivery now takes the stamp off with
SplitTimestamp and matches `^host program[pid]: <id>: to=<...>, ...
status=`, as queueLineRe and the inbound patterns do.

Tests: the probed HELO line, the same text in a quoted sender on a qmgr
line, the text after an smtpd line's queue id - none parse; a syslog-stamped
line as Postfix 3.7 writes it parses. The existing cases unchanged.

CHANGELOG [Unreleased], audit plan line ticked, roadmap 11/61.
Evidence: go test ./internal/logtail ok but for TestFollowTailsAndRotates
(Windows); the server run of the stage follows before the push.

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

docs/audit-2026-10-12.md

@@ -627,7 +627,7 @@ has already run is never edited — the next file is added; the published
    grown for a tick and the new file has a line). Both are fixes to the
    tailer's blindness and stay on the list whatever the sweep's fate; their
    priority follows `tailer_blind_seconds`.
-- [ ] **Anchor `deliveryRe`** at the head of the line like its two siblings;
+- [x] **Anchor `deliveryRe`** at the head of the line like its two siblings;
    test with the probed HELO and quoted-sender lines. — **Opus**
 - [ ] **TLS re-copy** (H2): `postfix-cert-reload.sh` compares the mounted files
    to the copy and re-copies before `postfix reload` (atomically, same modes);