Dagu has an incomplete fix for CVE-2026-27598: path traversal via %2F-encoded slashes in locateDAG

The fix for CVE-2026-27598 commit e2ed589, PR 1691 added ValidateDAGName to CreateNewDAG and rewrote generateFilePath to use filepath.Base. This patched the CREATE path. The remaining API endpoints - GET, DELETE, RENAME, EXECUTE - all pass the fileName URL path parameter to locateDAG without...