docs(review): finish the 5m->20m judge-default sweep

The 'restore 20m' commit updated the constant and the Long usage block but missed three references, leaving --help contradicting itself (flag string said 5m, usage block said 20m) — a user bounding CI cost would mis-estimate the judge's ceiling by 4x. Fixed the --timeout flag registration string, the judgeTimeoutArg doc comment, and the stale test comment.