Document x86 ISO builds and add container tooling
* Add a top-level README that documents the project layout, build flow, runtime expectations, and refreshed repository guidance.
* Add the x86 ISO GitHub Actions workflow so the bootable image path is exercised in CI.
* Introduce Docker-based build helpers via utils/Dockerfile and utils/docker.mk and wire the makefile into the container flow.
* Drop the checked-in freeze image artifacts from the repository root now that the build and documentation flow covers those outputs.
9 files changed,
153 insertions,
14 deletions