docs(sdk): add scoped AGENTS.md

[enyst]

Adds openhands-sdk/openhands/sdk/AGENTS.md following the structure suggested by the Codex /init prompt (concise repo-specific guidelines for structure, commands, style, testing, and PRs).

---

Agent Server images for this PR

• GHCR package: https://github.com/OpenHands/agent-sdk/pkgs/container/agent-server

Variants & Base Images

Variant	Architectures	Base Image	Docs / Tags
java	amd64, arm64	eclipse-temurin:17-jdk	Link
python	amd64, arm64	nikolaik/python-nodejs:python3.12-nodejs22	Link
golang	amd64, arm64	golang:1.21-bookworm	Link

Pull (multi-arch manifest)

# Each variant is a multi-arch manifest supporting both amd64 and arm64
docker pull ghcr.io/openhands/agent-server:a3f1586-python

Run

docker run -it --rm \
  -p 8000:8000 \
  --name agent-server-a3f1586-python \
  ghcr.io/openhands/agent-server:a3f1586-python

All tags pushed for this build

ghcr.io/openhands/agent-server:a3f1586-golang-amd64
ghcr.io/openhands/agent-server:a3f1586-golang_tag_1.21-bookworm-amd64
ghcr.io/openhands/agent-server:a3f1586-golang-arm64
ghcr.io/openhands/agent-server:a3f1586-golang_tag_1.21-bookworm-arm64
ghcr.io/openhands/agent-server:a3f1586-java-amd64
ghcr.io/openhands/agent-server:a3f1586-eclipse-temurin_tag_17-jdk-amd64
ghcr.io/openhands/agent-server:a3f1586-java-arm64
ghcr.io/openhands/agent-server:a3f1586-eclipse-temurin_tag_17-jdk-arm64
ghcr.io/openhands/agent-server:a3f1586-python-amd64
ghcr.io/openhands/agent-server:a3f1586-nikolaik_s_python-nodejs_tag_python3.12-nodejs22-amd64
ghcr.io/openhands/agent-server:a3f1586-python-arm64
ghcr.io/openhands/agent-server:a3f1586-nikolaik_s_python-nodejs_tag_python3.12-nodejs22-arm64
ghcr.io/openhands/agent-server:a3f1586-golang
ghcr.io/openhands/agent-server:a3f1586-java
ghcr.io/openhands/agent-server:a3f1586-python

About Multi-Architecture Support

• Each variant tag (e.g., a3f1586-python) is a multi-arch manifest supporting both amd64 and arm64
• Docker automatically pulls the correct architecture for your platform
• Individual architecture tags (e.g., a3f1586-python-amd64) are also available if needed

[all-hands-bot]

🟢 Good taste - Straightforward, practical documentation. This is exactly what scoped guidelines should look like: clear commands, real advice, no theoretical nonsense. LGTM.

[xingyaoww]

I wonder if our current SDK support loading this though?

[enyst]

I wonder if our current SDK support loading this though?

Not yet, coming up! 😅

For codex-cli it's just a prompt section. I'd try something similar, since we're rethinking a bit the prompt sections, WDYT?