ci(bluebuild): --security-opt label=disable + seccomp=unconfined for files module

BlueBuild's files module fails with 'chmod: Operation not permitted' on
its own bind-mounted /tmp/modules/files/files.sh when run under podman.
Disable SELinux relabeling + seccomp filter on the bluebuild CLI
container so its nested buildah can chmod inside layer mounts.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.github/workflows/build-bluebuild.yml

@@ -178,6 +178,8 @@ jobs:
 
           podman run --rm \
             --privileged \
+            --security-opt label=disable \
+            --security-opt seccomp=unconfined \
             --entrypoint /usr/bin/bluebuild \
             -v "$PWD:/work" \
             -v /var/lib/containers/storage:/var/lib/containers/storage \