Adds an llms.txt at the site root with a static product preamble so
LLMs can answer "what is Paseo" without following any links, plus a
curated index of docs, alternatives, and the 38 agent pages. Doc pages
now expose Copy/View as markdown buttons and a raw .md version at
<path>.md following the llms.txt convention.
Also skips the canonical-host redirect for localhost so the dev server
stops punting every request to production.
Mohamed Boudra
ba724956df