audit 4: findings of the two reviews

- Two inbound domains on one upstream could never change its TLS mode,
  each save refused for the other (medium): SetTransportAs changes the
  mode for every domain on the upstream when the one saving may change
  them all; a domain user who may not is refused with the mode, not the
  other tenant's domain name (security F1: the first version named it).
- A deletion's leftover DKIM key is removed by Resync (Reload
  configuration, a restore's first start) for names no domain has.
- The backup's write deadline moves before Check.
- hasUnsavedEdit skips password and file fields and compares a multiple
  select's options; htmx.config.timeout 30 s, so a refresh never answered
  ends and is tried again; a failed refresh's promise is handled.
- An empty filtered Outbound log says no message matches the filters.
- The dummy bcrypt hash is made at start; a DMARC part over 8 MiB is
  refused for its size like the other two limits.
- Health's Configuration box says what Reload writes (design first,
  32dfe4a).
- Docs: CHANGELOG, guide § Inbound, security.md (the shared upstream's
  mode, the profile form's "username taken"), architecture.md (owed to an
  address), the plan's notes corrected.
Tests: the shared upstream (service, handler), the leftover key, all eight
Health boxes ordered, the subject from before migration 0011, the new JS
cases.

Tested on the test server: go vet + go test of 25 packages, make e2e (all
pass, 636 s) on this tree.

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

internal/web/view/outbound_log.go

@@ -117,7 +117,7 @@ func NewOutLog(m Meta, retentionDays int, canSettings bool, domains, apps []stri
 		}
 		return out
 	}
-	return &OutLog{
+	p := &OutLog{
 		Meta: m,
 		Head: Head{Kicker: "Outbound", Title: "Outbound log", Lead: lead},
 		Messages: Box{No: "01", Title: "Messages", Help: topicLink(HelpLog, "What the statuses mean"), Filter: &Filter{
@@ -137,6 +137,12 @@ func NewOutLog(m Meta, retentionDays int, canSettings bool, domains, apps []stri
 		Foot:    Foot{ID: "out-log-foot", End: Plain("New rows appear on their own")},
 		filter:  f,
 	}
+	// Filtered to nothing is not an empty log (review of audit stage 4),
+	// as on the Inbound log.
+	if f != (OutLogFilter{}) {
+		p.Empty.Text = Plain("No messages match these filters.")
+	}
+	return p
 }
 
 // DetailHref is the address of one message's page, carrying the filters and the