feat: Added simple Docker build support for Mac/Windows users.

[skyzyx]

• Added Dockerfile and docker-compose.yml configuration which enables containerized builds, reducing local setup requirements.
• Updated README with build instructions for Docker alongside traditional setups, improving clarity and accessibility.

[Copilot]

Pull request overview

Adds containerized build support to reduce local setup friction (especially for Mac/Windows users) and updates documentation accordingly.

Changes:

• Expanded README build section with submodule-clone guidance plus Docker/non-Docker build paths.
• Added a Dockerfile intended to build the project inside a devkitPro-based container.
• Added a minimal docker-compose.yml to run the build against the repo via bind mount.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

File	Description
README.md	Documents cloning with submodules and adds Docker-based build instructions.
Dockerfile	Introduces a devkitPro-based build image intended to run make in /workspace.
docker-compose.yml	Defines a syspatch service to build using the Dockerfile with the repo mounted into the container.

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[Copilot]

The base image devkitpro/devkitarm is for 32-bit ARM and doesn’t match this project’s Switch/libnx toolchain (AArch64). CI builds in devkitpro/devkita64 (see .github/workflows/build-jobs.yaml:11), and both sysmod/Makefile and overlay/Makefile include $(DEVKITPRO)/libnx/switch_rules and target armv8-a. Update the Dockerfile to use the devkita64 image so switch-dev and the AArch64 compiler are available and the Docker build succeeds.

Suggested change

	FROM devkitpro/devkitarm:latest AS root
	FROM devkitpro/devkita64:latest AS root

[Copilot]

Using the :latest tag makes Docker builds non-reproducible and can break unexpectedly when the upstream image changes. Consider pinning to a specific devkitPro image tag (or digest) that matches what CI uses so local Docker builds remain stable.

Suggested change

	FROM devkitpro/devkitarm:latest AS root
	FROM devkitpro/devkitarm:<pinned-tag> AS root

[Copilot]

apt-get upgrade in the image build increases build time and reduces reproducibility (and can occasionally introduce breaking changes in the toolchain image). Prefer installing only the needed packages with --no-install-recommends and cleaning apt lists, without upgrading the full base image.

Suggested change

	RUN apt-get -y update && apt-get -y upgrade && \
	apt-get -y install \
	build-essential \
	git \
	zip \
	;
	RUN apt-get -y update && \
	apt-get -y install --no-install-recommends \
	build-essential \
	git \
	zip \
	&& rm -rf /var/lib/apt/lists/*

[Copilot]

This instruction likely points to the wrong toolchain for Nintendo Switch builds. The project uses libnx/switch_rules and -march=armv8-a... (AArch64), so users typically need devkitPro with devkitA64 (not devkitARM). Updating the wording here will prevent failed local builds.

Suggested change

	1. Install [devkitARM](https://devkitpro.org/wiki/Getting_Started).
	1. Install [devkitPro with devkitA64](https://devkitpro.org/wiki/Getting_Started).

[Copilot]

For a one-shot build container, docker compose up is a bit awkward because it creates/stops a named service container and may require manual cleanup/re-runs. Consider documenting docker compose run --rm syspatch (or up --abort-on-container-exit) to better match the intended “run build then exit” workflow.

Suggested change

	docker compose up --build
	docker compose run --rm syspatch

[Copilot]

With the bind mount, the container runs as root by default, so build artifacts written into the repo (e.g., out/, build/) will be owned by root on Linux hosts. Consider setting a user: (UID:GID) in the compose service or documenting this caveat so users don’t end up with permission issues when running Docker builds locally.

Suggested change

	context: .
	context: .
	user: "${UID:-1000}:${GID:-1000}"