Fix: llms.txt

Curated markdown index for agents. Serve at /llms.txt. Include an H1, a short summary, and H2 sections with absolute links. This helps agent discoverability. It is not a search-ranking signal.

# Your Site Name

> One sentence on what the site does.

## Docs

- https://yourdomain.com/docs

## Product

- https://yourdomain.com/

Spec: llmstxt.org