fix(gh): account for every check bucket in the pr checks summary

Filtering a failing `gh pr checks` makes the summary the only thing the user
sees, so a bucket it does not count disappears. `parse_pr_check_line` dropped
every row that was not pass/fail/pending, which turned a cancelled run -- the
usual outcome when a new push supersedes CI -- into "Passed: 0, Failed: 0",
and left 5 of PR 3982's 15 checks out of the totals.

Count the remaining buckets and report them, so the summary always adds up to
the checks gh listed.

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