Update prompt text, attributes, or active flag

Editing prompt text after results exist requires an explicit choice. The first call returns 409 with requiresConfirmation: true (plus tracked and inFlightRun hints); resend with confirmClone: true to clone-and-supersede (the original is deactivated with its history intact — recommended for tracked prompts) or confirmOverwrite: true to edit in place (unavailable while a run is in flight).