CI builds firmware inside the espressif/idf Docker image, but this
sandbox can't run containers at all -- it strips cap_sys_admin (and
blocks unshare) from the capability set even for root, which container
image-layer extraction and namespace setup both need. Confirmed by
hand: docker.io installs and dockerd starts fine, but even a bare
`docker run hello-world` fails to extract its own layer.
Works around it by installing ESP-IDF natively instead (git clone +
its own install.sh, scoped to just this project's esp32c6 target) --
the same way a developer would set it up on their own machine, needing
nothing this sandbox disallows. Verified end-to-end: both board
variants (devkit, xiao) build clean from a fresh checkout via the
packaged setup.sh/build.sh.
tfaour
8602ee3add