fix(ci): drop ssh-keyscan, use StrictHostKeyChecking=accept-new instead

ssh-keyscan fails when the runner can't reach the host on port 22
during that step. Using accept-new on the ssh command itself is
equivalent for an ephemeral CI runner.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/sync-images.yml

@@ -26,13 +26,12 @@ jobs:
       - name: Set up SSH key
         run: |
           mkdir -p ~/.ssh
-          echo "${{ secrets.PRIVATE_SSH_KEY }}" > ~/.ssh/deploy_key
+          printf '%s\n' "${{ secrets.PRIVATE_SSH_KEY }}" > ~/.ssh/deploy_key
           chmod 600 ~/.ssh/deploy_key
-          ssh-keyscan -p 22 "${{ secrets.APP_HOST }}" >> ~/.ssh/known_hosts 2>/dev/null
 
       - name: Sync images to server
         run: |
-          SSH_CMD="ssh -i ~/.ssh/deploy_key -p 22 root@${{ secrets.APP_HOST }}"
+          SSH_CMD="ssh -i ~/.ssh/deploy_key -o StrictHostKeyChecking=accept-new -p 22 root@${{ secrets.APP_HOST }}"
 
           IMAGES=(
             gitea.siegeln.net/cameleer/cameleer-saas:latest