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

frontend/components/workflow/workflow-lifecycle.tsx

@@ -294,7 +294,7 @@ export function WorkflowLifecycle({
                     type="button"
                     className="ml-0.5 hover:text-destructive"
                     onClick={(e) => { e.stopPropagation(); removeUploadedFile(f.publicId); }}
-                    aria-label={t('workflow.timeline.uploadError')}
+                    aria-label={t('workflow.timeline.removeFile')}
                   >
                     <XIcon className="h-3 w-3" />
                   </button>