fix: use printf for SSH key to preserve trailing newline

Co-authored-by: Cursor <cursoragent@cursor.com>

.forgejo/workflows/main_service-main-llm-private.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Setup SSH
         run: |
           mkdir -p ~/.ssh
-          echo "${{ secrets.SSH_PRIVATE_KEY }}" > ~/.ssh/deploy_key
+          printf '%s\n' "${{ secrets.SSH_PRIVATE_KEY }}" > ~/.ssh/deploy_key
           chmod 600 ~/.ssh/deploy_key
           ssh-keyscan -H ${{ env.SERVER_HOST }} >> ~/.ssh/known_hosts