Could Katalon support @manual testing?

That would be for the developers to decide.

That’s an implementation detail. I can imagine @manual being a “mode” which would need to be selected at Test Case startup (the current execution structure would need to be modified to support it). Then, I can imagine WebUI.manualAsk(“Prompt user”) type calls being made available.

But again, these are implementation details – pointless to discuss them at length.