ci: ANTHROPIC_API_KEY 未設定時はジョブをスキップ

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Author: striderkein

.github/workflows/grade-pr.yml

@@ -10,6 +10,7 @@ permissions:
 
 jobs:
   grade:
+    if: ${{ secrets.ANTHROPIC_API_KEY != '' }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4