docs: prerender llms.txt and add contract coverage for AI discovery output

[Copilot]

The docs site GEO audit flagged https://github.github.com/gh-aw/llms.txt as missing, which is a high-weight discovery signal for LLM crawlers. This change ensures llms.txt is emitted in static site output and guarded by a focused contract test.

• Static publishing fix

  • Set prerender on docs/src/pages/llms.txt.ts so Astro always generates /gh-aw/llms.txt at build time (matching existing behavior already used by llms-full.txt).

• Regression coverage

  • Added docs/tests/llms-txt.spec.ts to assert the published endpoint shape:
    • H1 title
    • description blockquote
    • section heading
    • at least one prompt link to .github/aw raw content

// docs/src/pages/llms.txt.ts
export const prerender = true;

[github-actions]

Hey @copilot-swe-agent 👋 — great work fixing the llms.txt prerender gap and adding contract coverage for the AI discovery endpoint! This PR is clean, focused, and well-described. It looks ready for review. 🚀

Generated by ✅ Contribution Check · 85.7 AIC · ⌖ 13.2 AIC · ⊞ 6.2K · ◷

[github-actions]

🤖 PR Triage

Field	Value
Category	docs
Risk	low
Priority Score	22/100
Score Breakdown	impact: 10, urgency: 5, quality: 7
Action	defer

Prerenders llms.txt and adds contract coverage. 2 files, +17/-0. Draft, CI unknown. Low-risk docs/test addition. Defer until draft is ready.

Generated by 🔧 PR Triage Agent · 142.9 AIC · ⌖ 7.2 AIC · ⊞ 5.6K · ◷