docs(skills): add gnhf orchestration skill

[Arcadia822]

Add a gnhf skill that helps an outer coding agent operate GNHF as the execution loop for long-running agent work.

The user-authored contribution here is the skills/gnhf/SKILL.md skill itself. The package metadata, README/AGENTS documentation updates, and focused packaging test were added after no-mistakes review/test/documentation feedback so the skill is actually shipped and documented with the npm package.

The skill keeps the surface area intentionally small: it distinguishes Hands-Off runs from Companion-supervised runs, provides a launch prompt skeleton, and documents when companion steering, follow-up findings, and morning review should happen. The package file list now includes skills so the skill is published with the npm package, and the README points users to the bundled skill file.

Agent-Managed Runs

The skill gives host agents a repeatable way to translate a user request into a GNHF invocation with explicit constraints, verification expectations, and an observable stop condition. Both modes include short English and Chinese examples to make trigger intent clear.

Example Hands-Off requests:

I'm going to bed. Use GNHF with Copilot to keep working on this branch and stop when the test suite passes.

我要睡了。用 GNHF 接着跑这个分支，测试都过了就停。

Companion Supervision

Companion-only sections cover steering, review, and review-finding follow-up so agents do not confuse hands-off execution with active quality supervision.

Example Companion requests:

Run GNHF for a few rounds on this onboarding flow. Check the diff between rounds and tighten the next prompt if it starts polishing the wrong thing.

用 GNHF 多跑几轮这个 onboarding 流程。每轮看一下 diff，如果它开始改偏了，就收窄下一轮 prompt。

Validation

• Added a focused Vitest check that validates the skill frontmatter and confirms skills/gnhf/SKILL.md is included in npm pack --dry-run --json.
• Updated AGENTS.md so the package description no longer implies the npm artifact is only a single-file bundle.

Pipeline

Updates from git push no-mistakes:

• Review: passed, low risk, no findings.
• Test: passed with npx vitest run test/gnhf-skill.test.ts after npm ci in the isolated worktree.
• Document: passed, no documentation gaps found.
• Lint: passed with Prettier, ESLint, and TypeScript typecheck.

Note: no-mistakes briefly pushed an extra excalidraw.log in an auto-generated follow-up commit. That file was unrelated and was removed before opening this PR.

Refs #98

[Arcadia822]

Any files besides the SKILL.md file comes from the no-mistake workflow. I'm not familiar with typescript development / testing. If you don't mind, I will remove the test.

[kunchenguid]

Thanks @Arcadia822 - the skill content looks great and matches what we discussed in #98. Could you rebase on main? The branch is ~19 commits behind and your AGENTS.md edit will conflict with the recent ACP wording on that same line. While you're in there, it would be nice (but not required for this PR) to add acp:<target> to the skill's agent list so it stays accurate on day one. The packaging test you flagged is fine to drop - your call.

[kunchenguid]

@Arcadia822 i just resolved the conflict and merged. thank you for the contribution!