Fix deployment: stop service before copying binary

The previous deploy was failing with "Text file busy" because the deploy
script tried to cp the new binary over the running process. Add an SSH
step to stop the moon service before running deploy-moon, so the binary
is no longer in use when it gets replaced.

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

Author: exploded

.github/workflows/deploy.yml

@@ -57,6 +57,15 @@ jobs:
           target: "/tmp/moon-deploy"
           overwrite: true
 
+      - name: Stop service before deploy
+        uses: appleboy/ssh-action@v1.0.3
+        with:
+          host: ${{ secrets.DEPLOY_HOST }}
+          username: ${{ secrets.DEPLOY_USER }}
+          key: ${{ secrets.DEPLOY_SSH_KEY }}
+          port: ${{ secrets.DEPLOY_PORT || '22' }}
+          script: sudo systemctl stop moon
+
       - name: Install and restart service
         uses: appleboy/ssh-action@v1.0.3
         with: