Answer the domain's questions about a report

What the reporter answered to the questions the domain's owner asks, posted after the report they belong to rather than with it - the panel asks them once the share link is already on screen. Two ways to be allowed: anonymously, with the replay id in the path AND the extension id the report was filed with, both matching the stored report; or signed in, as the report's own submitter. The share token is not a key here - it exists to be forwarded. A report filed through the integration library carries no extension id, so it can only be answered by a signed-in submitter. Posting again replaces the previous answers, so a retry is harmless. Every refusal of the poster is the same 404, whatever was wrong. The whole request may not exceed 64 KB; one that does, or one that declares no length, is refused with 413 and the error code 'answers_too_large'.