Expose a direct Sandbox runtime factory

[ggoodman]

Summary

• replace the public createSandboxNodeRuntimeHost seam with createSandboxNodeRuntime
• keep the caller-owned SandboxInstance lifecycle while making the Node host composition internal
• update the README example to persist VM state in .torkbot/rootfs.qcow2 and mount the workdir read-only with /.git, /.torkbot, and /node_modules masked

Why

The previous API required every caller to construct Node24Runtime with the return value of a Sandbox host factory. That exposed an internal ownership boundary without adding useful caller composability. This package owns the integration, so it should return the completed runtime while callers continue to own and configure the Sandbox itself.

This intentionally replaces the 0.1 API rather than preserving a compatibility alias.

Validation

• npm run typecheck
• npm test (9 tests)
• npm run build
• npm pack --dry-run --ignore-scripts
• git diff --check

[ggoodman]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Nice work!

Reviewed commit: fe2c816786

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".