fix: SSH 키 base64 디코딩 스텝 추가

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/deploy.yml

@@ -24,13 +24,18 @@ jobs:
       - name: Build
         run: npm run build
 
+      - name: Decode SSH key
+        run: |
+          echo "${{ secrets.SSH_PRIVATE_KEY }}" | base64 -d > ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+
       - name: Deploy via SCP
         uses: appleboy/scp-action@v0.1.7
         with:
           host: ${{ secrets.SSH_HOST }}
           port: ${{ secrets.SSH_PORT }}
           username: root
-          key: ${{ secrets.SSH_PRIVATE_KEY }}
+          key_path: ~/.ssh/id_ed25519
           source: dist/*
           target: /var/www/proto.bodalab.diffthink.kr/
           strip_components: 1