Name ci-test job "CI" for a searchable status check (#224)

Give the check job an explicit name so branch protection rules can
reference a stable, searchable "CI" status check context instead of
the generic job-key-derived name.

Co-authored-by: Claude Opus 4.8 (1M context) <[email protected]>

.github/workflows/ci-test.yml

@@ -10,6 +10,7 @@ concurrency:
   cancel-in-progress: true
 jobs:
   check:
+    name: CI
     runs-on: ubuntu-latest
     steps:
       - name: Checkout