test(gh): use gh's real row shape in the pr checks tests

`gh pr checks` spells a pending bucket `pending`, never `*`, and prints five
tab-separated fields with the description last. The transition test used a
shape gh does not emit; the new case carries the trailing description column
and a pending row that resolves across polls.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>