fix: clean up leftover container before pi-gen build

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

.gitea/workflows/build-sd-image.yml

@@ -49,6 +49,9 @@ jobs:
 
       - name: Build SD image in Docker
         run: |
+          # Clean up any leftover container from a previous failed build
+          docker rm -f tipote-build 2>/dev/null || true
+
           # Run pi-gen build inside a privileged container
           # Use docker cp (not volume mounts) because of DooD path mapping
           docker run --privileged --name tipote-build tipote-builder