inbound-antispam-panel: three things the reviews left as found

The owner asked for them to be put right (2026-10-12).

  - A refusal is not logged twice after an unclean stop. The tailer
    saves its place every five seconds, so on start it reads some
    lines again; for the lines it reads on start a row is written only
    if the same row is not there already (store.InsertInboundSpamOnce:
    same moment, client, sender, recipient, decision, engine, detail).
    Lines read as they are written are always new, so two identical
    refusals in one second stay two rows.
  - The Inbound log offers Deny / Allow sender only for a sender the
    lists would take (inbound.Listable): an envelope sender may be
    spelt in ways the form refuses, and the link led to a refusal.
  - A network of one address is stored as the address: 192.0.2.7/32
    and 192.0.2.7 were two entries of one list.

Checked on the test server, uncommitted tree: go vet ./... ok,
go test ./... ok (22 packages), make e2e ok.

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

docs/architecture.md

@@ -97,9 +97,9 @@ smtp/inet` removes Debian's stock smtpd). Outbound delivery still uses the
   line, when the recipient is at an inbound domain
   ([internal/logtail/inbound.go](../internal/logtail/inbound.go)). A line
   names one recipient, so a message refused at end-of-message is one row
-  whatever its recipient count, and a line read twice (the tailer saves its
-  place every five seconds; an unclean stop can lose those seconds) is two
-  rows. The
+  whatever its recipient count. The tailer saves its place every five seconds,
+  so after an unclean stop it reads some lines again; the lines it reads on
+  start are written only if the same row is not there already. The
   journal is pruned every six hours: rows
   older than the `inbound_spam_log_retention_days` setting, then down to
   10 000.