Adding llms.txt

[jrupp]

Adding an llms.txt in line with https://llmstxt.org/ for use by LLMs to easily learn about BrickLayouts

[Copilot]

Pull request overview

Adds an llms.txt file (per llmstxt.org guidance) so AI agents can quickly understand BrickLayouts’ purpose and find authoritative links for product, pricing, and legal/policy pages, and documents this convention in contributor guidance.

Changes:

• Added public/llms.txt with a curated product/site summary and canonical links to key pages.
• Updated CLAUDE.md to document the purpose/location of llms.txt and to keep it updated as content changes.
• Updated .github/copilot-instructions.md to reflect the presence and maintenance expectations of public/llms.txt.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
public/llms.txt	Introduces an LLM-readable overview of BrickLayouts and links to core pages, app, roadmap, and legal docs.
CLAUDE.md	Adds contributor guidance about public/llms.txt and keeping it in sync with site content.
.github/copilot-instructions.md	Documents llms.txt in the project layout and architecture notes for Copilot guidance.