Accept Cover Ask Link

One tap accepts a cover ask -- from the link's page.

⛔outcome.reason IS THE REAL ANSWER, NOT outcome.handled. employee_reply.accept_cover_ask always reports handled=True for a cover ask -- record_answer's own rule, "the arrival is recorded whatever the verdict" -- so a late or already-answered tap still comes back handled=True with reason naming why it did not apply. The state != 'open' check above catches the common case; this catches the race where it changed between that read and this write.