Docs: search, a table of contents, and a page for calling the API without the packages

Calling the API directly documents the whole contract in plain HTTPS and JSON: the keyless root endpoint, one geocode-then-route program as curl, fetch and Python, and a stock MapLibre page. The rest of the docs got the furniture a reference needs.

• Full-text search over both languages, from the sidebar or ⌘K
• Code tabs: npm, pnpm, yarn and bun on every install block, a fetch twin for every curl example, and the choice remembered across pages
• A table of contents on wide screens that tracks the heading you are reading