send log: rows belong to a domain by id (audit L12, 0008)

A domain user's log, the message page, a domain's statistics, the level-2
count and the notifier's refusal count picked send-log rows by domain name,
so a domain deleted and re-added under its old name showed its earlier mail
to the next assignee and went on counting it.

Migration 0008 (not run on the live database yet, so extended here):
send_log.domain_id and inbound_spam_log.inbound_domain_id, REFERENCES ...
ON DELETE SET NULL, filled once by name from the registry as it is at
migration time, each with an (id, created_at) index.

- Writes: InsertQueued / InsertRejected set domain_id to the domain of the
  row's login (loginDomainID) - the journal milter and the sender check's
  refusal rows both go through them; the inbound journal sets
  inbound_domain_id from the inbound domain's name at insert.
- Reads: SendLogFilter.DomainIDs (was Domains, by name) and
  InboundSpamFilter.DomainIDs are the scope; the global role still reads
  everything. The message page checks row.DomainID against the user's
  domains. DomainSendStats and CountMessages keep their name argument and
  select domain_id = (SELECT id FROM domains WHERE name = ?). The notifier
  joins send_log.domain_id to the domain and its application.
- DMARC reports stay by name on purpose (a report is about the DNS name).

Tests: store - scope by ids; a re-added domain's log, level-2 count and
statistics hold its own row only, the global log both; inbound scope by
ids. Handlers - the new assignee gets 404 for the old row's page and does
not see it in the log, the global role sees both. Tests that wrote rows for
a login that is no application now register it (a row is a domain's through
its application). Schema at 0008 with the two columns and indexes.

schema-migrations row 8, CHANGELOG [Unreleased], audit plan line ticked,
roadmap 19/62.
Evidence: go vet ./... clean; go test ./... ok locally but for the two
Windows-only tests; the server run follows before the push.

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

internal/store/ratelimits.go

@@ -170,13 +170,17 @@ func (s *Store) RateLimit(scope, ref string) (RateLimit, bool, error) {
 // semantics — and excludes rows that were themselves rejected by a limit (they
 // were never sent). It reuses the send log the journal already writes (README
 // § Rate limiting — the limiter reuses the send log).
+//
+// A domain's messages are the rows of the domain registered under ref now, by
+// id: rows a deleted domain of the same name left behind are not its (audit
+// 2026-10-12, L12).
 func (s *Store) CountMessages(scope, ref string, since time.Time) (int64, error) {
-	var column string
+	var match string
 	switch scope {
 	case RateLimitScopeDomain:
-		column = "domain"
+		match = domainByName
 	case RateLimitScopeApp:
-		column = "app_login"
+		match = "app_login = ?"
 	default:
 		return 0, fmt.Errorf("unknown rate-limit scope %q", scope)
 	}
@@ -185,7 +189,7 @@ func (s *Store) CountMessages(scope, ref string, since time.Time) (int64, error)
 	// same format is chronologically correct (as in DeleteSendLogBefore).
 	err := s.db.QueryRow(
 		`SELECT COUNT(DISTINCT queue_id) FROM send_log
-		 WHERE `+column+` = ? AND status != ? AND created_at >= ?`,
+		 WHERE `+match+` AND status != ? AND created_at >= ?`,
 		ref, StatusRejected, since.UTC().Format(time.RFC3339),
 	).Scan(&n)
 	if err != nil {