fix(scheduler): убрать двойной SaveCheckRun (Checker персистит), SetDrift через CountDriftDomains, resolved после error

internal/store/tenant.go

@@ -258,6 +258,14 @@ func (s *Store) SetDomainStatus(ctx context.Context, domainID uuid.UUID, status
 	return s.q.SetDomainStatus(ctx, db.SetDomainStatusParams{ID: domainID, LastCheckStatus: status})
 }
 
+// CountDriftDomains returns the current number of domains system-wide whose
+// last check status is "drift". This is a global count (not per-project) —
+// it backs the dns_ar_drift_domains gauge, which is a system-level metric.
+func (s *Store) CountDriftDomains(ctx context.Context) (int, error) {
+	n, err := s.q.CountDriftDomains(ctx)
+	return int(n), err
+}
+
 // User and Project are provider-neutral domain structs for the auth/tenant
 // layer (Фаза 2), mirroring the Account/Template/Domain wrappers above so
 // callers never need to import internal/store/db directly.