docs(site): Fumadocs documentation site on TanStack Start

New standalone app at docs-site/ — Fumadocs (fumadocs-core/ui 16, fumadocs-mdx
15) on TanStack Start (Vite 7 + nitro-v2 bun preset, React 19, Tailwind 4),
mirroring the web/ console stack but with no auth/i18n/orval — docs stay public.

- catch-all docs route (routes/docs/$.tsx), Orama search (routes/api/search.ts),
  RootProvider shell, MDX component map, shared nav, custom 404
- content/docs/: hand-written index.mdx + meta.json nav, plus 7 pages imported
  from repo docs/ + README (leading H1 stripped, YAML frontmatter added; kept as
  .md so existing </{ don't trip MDX JSX). Content is a one-time snapshot.
- mdx() is plugins[0]; tsconfig collections/* -> ./.source/*; SSR search variant;
  @source for fumadocs-ui classes. Generated .source/routeTree/dist/.output ignored.

Verified: bun run build (client+SSR+nitro) green, tsc clean, dev + prod servers
serve all routes 200 with SSR content + nav, search returns hits, 404 works.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs-site/README.md

@@ -0,0 +1,39 @@
+# punktfunk-docs
+
+The punktfunk documentation site: [Fumadocs](https://fumadocs.dev) on
+[TanStack Start](https://tanstack.com/start) (Vite + Nitro/bun preset).
+
+Content lives in [`content/docs/`](content/docs) as `.md`/`.mdx`. Several pages are imported
+verbatim from the repo's `docs/` design notes (with added frontmatter); edit those there or
+here as the docs site becomes the source of truth.
+
+## Develop
+
+```sh
+bun install
+bun run dev        # http://localhost:3001  (docs at /docs)
+```
+
+## Build & serve
+
+```sh
+bun run build
+bun run start      # serves .output/ via Bun
+```
+
+## Layout
+
+```
+source.config.ts          Fumadocs MDX collection (content/docs)
+content/docs/             the docs content (.md/.mdx) + meta.json nav
+src/
+  routes/
+    __root.tsx            RootProvider + html shell
+    index.tsx            landing page
+    docs/$.tsx           catch-all docs renderer (Fumadocs DocsLayout)
+    api/search.ts        Orama search endpoint
+  lib/source.ts          Fumadocs loader over the generated collection
+  lib/layout.shared.tsx  shared nav chrome
+  components/mdx.tsx      MDX component map
+  styles/app.css          Tailwind 4 + Fumadocs preset
+```