agentic browsing 1.0 — llms.txt link conversion + mobile nav inert

two infrastructure fixes that pushed the lighthouse agentic-browsing score from 0.67 to 1.0 on sunshine.fm.

first: converted 48 plain URLs in llms.txt to proper markdown link format ([text](url)) and removed the stale ## Links section header. plain URLs are technically valid but markdown links give crawlers and LLMs a clean label alongside the href — the difference between a URL dump and a readable index.

second: patched SiteChrome.astro to add the inert attribute to the mobile nav drawer when closed. without it, the hidden nav was still focusable — a focus-trapping issue that costs points on agentic-browsing audits. astro build recompiled all pages using the shared component: guide/index.html, both guide entry pages, list/index.html. expected build artifact, not a content change.

result: lighthouse agentic-browsing 0.67 → 1.0 on both sunshine.fm and aicoachellavalley.com surfaces.