ai-agents: serve /llms-full.txt with full docs + component summaries

[bntvllnt]

Problem

`/llms.txt` (companion issue) is an index. Agents that want full context still need to make N requests. `/llms-full.txt` provides everything inline.

Goal

One-fetch, complete agent context: install instructions, philosophy, docs, every component name + description + dependencies.

Acceptance criteria

• Route handler at `apps/registry/app/llms-full.txt/route.ts` returns `text/plain`.
• Content includes:
  • Install + CLI usage (from `docs.mdx` + `home.mdx`)
  • Full philosophy text (`philosophy.mdx`)
  • All 4 `content/pages/*.mdx` bodies
  • Per-component block: name, description, category, dependencies, registryDependencies, install command, link to `/r/.json`
• Component source code NOT inlined (link only — keeps file size manageable).
• Generated from `registry.json` + MDX content at request/build time.
• Cache-Control header set (revalidate daily).
• Response under 1MB.

References

• Spec: https://llmstxt.org
• Example: https://docs.anthropic.com/llms-full.txt

Depends on

• llms.txt issue (build the index first, reuse the data layer)