fix(workflow): ADR-021 code review fixes (8 bugs)

- fix(transmittal): guard duplicate workflow instance on submit()
- fix(workflow-guard): add organizationId to context so Level-2 RBAC works
- fix(circulation): organizationId context passed relation object not INT FK
- fix(transmittal): require Idempotency-Key header on POST submit endpoint
- fix(workflow): userId non-optional in processTransition controller
- fix(circulation): auto-close counts PENDING and IN_PROGRESS tasks
- fix(transmittal): status badge uses workflowState/DRAFT not purpose field
- fix(workflow): log cache invalidation failures instead of swallowing
- fix(workflow): implement getAvailableActions endpoint stub
- fix(i18n): add removeFile key to EN/TH locales

backend/src/modules/workflow-engine/workflow-engine.service.ts

@@ -387,7 +387,13 @@ export class WorkflowEngineService {
       await queryRunner.commitTransaction();
 
       // ADR-021 T043: Invalidate Workflow History cache หลัง transition สำเร็จ
-      void this.cacheManager.del(`wf:history:${instanceId}`);
+      this.cacheManager
+        .del(`wf:history:${instanceId}`)
+        .catch((e: unknown) =>
+          this.logger.warn(
+            `Cache invalidation failed for wf:history:${instanceId} — stale data may be served. Error: ${e instanceof Error ? e.message : String(e)}`
+          )
+        );
 
       // [NEW] เก็บค่าไว้ Dispatch หลัง Commit
       eventsToDispatch = evaluation.events;