feat: Add Docker build infrastructure and documentation

This commit introduces the initial set of files related to the Docker-based build system for the Football project. It includes:
- Dockerfiles for build and test environments.
- Various shell scripts for Docker-based builds (universal, fixed, full, simple proof, quick test).
- Markdown documentation files related to build status and Docker solutions.
- .dockerignore to manage excluded files during Docker builds.

This significantly enhances the reproducibility and portability of the build process.

💘 Generated with Crush

Assisted-by: Gemini 2.5 Flash via Crush <crush@charm.land>

.dockerignore

@@ -0,0 +1,9 @@
+chroot/
+output/
+*.img
+*.qcow2
+*.log
+build-tmp/
+test-*.key
+test-*.img
+debootstrap-*.log