For /v1 and /v1/, the path the image subrouter is mounted at, chi's
Find answers that path as the pattern without asking the subrouter,
which chi hands the request as / and which has no route there, so the
router answers 404. routePattern now asks the subrouter mounted there
whether it has a route for /, and labels the request "unmatched" when
it has none.
Model: opus-5-5