feat(api): GET /dictionaries/{name}/changelog — schema versions timeline (backend #1)

Backend #1 из pending-endpoints brief. Frontend HistoryTabContent +
TimeTravelModal используют этот endpoint для отображения версий схемы
во времени с per-version property-level diff summary.

Implementation:
- AuditLogger.definitionCreated / definitionUpdated — пишет в audit_log
  с event_type DEFINITION_CREATED / DEFINITION_UPDATED. payload_before/
  after = JsonNode schema. record_id / business_key — NULL (dict-level event).
- DictionaryDefinitionService.create / updateSchema hook в audit logger
  (autowired, null-safe для tests).
- AuditLogRepository.findByDictionaryIdAndEventTypes — query by dict_id +
  event_type IN (...), ORDER BY event_time DESC, paginated.
- ChangelogService.findChangelog — собирает entries, computes top-level
  property-key diff (added/removed/changed). Первая entry (newest) =
  isCurrent + schemaVersion из DictionaryDefinition; старые entries
  возвращают version=null (semver-в-аудит backfill — separate migration).
- DictionaryChangelogController — GET /dictionaries/{name}/changelog?limit=50

Errors:
- 404 dictionary_not_found когда dict missing OR scope hidden (consistent
  с другими endpoints).

Tests +9: dict-not-found, scope-hidden, empty-audit, first-is-current,
diff-added/removed/changed/null-before/identical.

ordinis-domain/src/main/java/cloud/nstart/terravault/ordinis/domain/audit/AuditLogRepository.java

@@ -14,6 +14,22 @@ public interface AuditLogRepository extends JpaRepository<AuditLog, Long> {
 
   List<AuditLog> findByDictionaryIdOrderByEventTimeDesc(UUID dictionaryId);
 
+  /**
+   * Audit entries для конкретного dict, отфильтрованные по event_type IN
+   * списке. Используется ChangelogService — берёт только DEFINITION_*
+   * events, skip RECORD_* шум.
+   */
+  @Query("""
+      SELECT a FROM AuditLog a
+      WHERE a.dictionaryId = :dictionaryId
+        AND a.eventType IN :eventTypes
+      ORDER BY a.eventTime DESC
+      """)
+  List<AuditLog> findByDictionaryIdAndEventTypes(
+      @Param("dictionaryId") UUID dictionaryId,
+      @Param("eventTypes") List<String> eventTypes,
+      Pageable pageable);
+
   List<AuditLog> findByRecordIdOrderByEventTimeDesc(UUID recordId);
 
   List<AuditLog> findByUserIdOrderByEventTimeDesc(String userId);