Both prefix pages passed the URL text to the lookup as typed. A prefix
that does not parse made the lookup fail with an error that was not "no
route found", so the pages answered 500; a valid prefix written in any
form other than the one the tables store answered 404 although the
route exists. Both handlers now parse the prefix with net/netip, mask
it and look up the text form it prints, and answer 400 for a prefix
that does not parse.
Model: opus-5-5