[abhishekgahlot2]

Adds a Fumadocs site in deepgym/docs-site/ that renders deepgym/docs/ as a static export.

• Content is read from deepgym/docs/ directly; page titles come from each file's first heading. Only meta.json files (order and groups) and a short docs/index.md are added; no existing doc changed.
• Sidebar: Getting started, Environments, Authoring, Training, Reference; built-in search; light and dark mode. rl-primer.html is served as-is.
• bun run build runs next build and a link check over every exported page and anchor; a broken link fails the build.
• CI: a docs-site job installs with the frozen lockfile, lints and builds.
• docs-site is excluded from the sdist.

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[abhishekgahlot2]

Closing: the docs site already exists in deepgym-landing (docs-site/, Blume), built from deepgym/docs at deploy time and served at https://deepgym.io/docs.