Studio's install_llama_prebuilt.py default policy expects a
llama-prebuilt-manifest.json asset on the published release, which
unslothai/llama.cpp ships but the upstream ggml-org/llama.cpp does
not. Without --simple-policy the resolver falls back to source
build with the message "published release ggml-org/llama.cpp@b9049
did not expose a usable llama.cpp manifest".
setup.sh passes --simple-policy in this exact configuration; mirror
that here so the CI step exercises the same path Studio takes on
macOS.