Remove the unused HubWorkflow type file #9108

Task Summary

frontend/src/app/hub/component/type/hub-workflow.interface.ts (exports HubWorkflow) has no importer, and it is the only file in hub/component/type/. No code, spec, barrel file or path alias references the file or the interface.

Introduced by #2725 (2024-09-24, "Add Hub"), for the hub workflow list.

Usage removed by #2928 (2024-10-29, "Add landing page"), which deleted the components that listed workflows with it. #3252 (2025-02-09, "Refactor APIs related to Hub interaction activities") then deleted the last, already unused, importer.

Deleting the file is a pure deletion with no behaviour change.

Task Type

• Refactor / Cleanup