feat(idempotency): scheduled cleanup для expired keys

@Scheduled(cron='0 17 * * * *') запускает deleteExpired раз в час (17-я
минута, чтобы не совпало с другими cron). Конфигурируется через
ordinis.idempotency.cleanup-cron. Counter ordinis_idempotency_cleaned_total
для observability.

ordinis-rest-api/src/main/java/cloud/nstart/terravault/ordinis/restapi/idempotency/IdempotencyCleanupJob.java

@@ -0,0 +1,46 @@
+package cloud.nstart.terravault.ordinis.restapi.idempotency;
+
+import cloud.nstart.terravault.ordinis.domain.idempotency.IdempotencyKeyRepository;
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.MeterRegistry;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+
+import java.time.OffsetDateTime;
+
+/**
+ * Scheduled cleanup для idempotency_keys.
+ *
+ * <p>Retention 30 дней (см. migration 0006). Запускается раз в час, удаляет
+ * записи с expires_at &lt; now. Неблокирующий — простой DELETE по индексу.
+ */
+@Component
+public class IdempotencyCleanupJob {
+
+  private static final Logger log = LoggerFactory.getLogger(IdempotencyCleanupJob.class);
+
+  private final IdempotencyKeyRepository repository;
+  private final Counter cleanedCounter;
+
+  public IdempotencyCleanupJob(IdempotencyKeyRepository repository, MeterRegistry meterRegistry) {
+    this.repository = repository;
+    this.cleanedCounter = Counter.builder("ordinis_idempotency_cleaned_total")
+        .description("Удалённые expired idempotency keys")
+        .register(meterRegistry);
+  }
+
+  @Scheduled(cron = "${ordinis.idempotency.cleanup-cron:0 17 * * * *}")
+  public void cleanup() {
+    try {
+      int deleted = repository.deleteExpired(OffsetDateTime.now());
+      if (deleted > 0) {
+        log.info("Idempotency cleanup: удалено {} expired ключей", deleted);
+        cleanedCounter.increment(deleted);
+      }
+    } catch (Exception e) {
+      log.warn("Idempotency cleanup failed: {}", e.getMessage());
+    }
+  }
+}