feat: add Docker setup for documentation site

- Dockerfile.docs for building docs container
- nginx.conf for serving static Starlight site
- docker-compose.yml updated with docs service (--profile docs)
- Updated docs installation/deployment pages

Dockerfile.docs

@@ -0,0 +1,18 @@
+FROM oven/bun:1.1-alpine AS builder
+
+WORKDIR /app/docs
+
+COPY docs/package.json ./
+RUN bun install
+
+COPY docs ./
+RUN bun run build
+
+FROM nginx:alpine
+
+COPY --from=builder /app/docs/dist /usr/share/nginx/html
+COPY docs/nginx.conf /etc/nginx/http.d/default.conf
+
+EXPOSE 80
+
+CMD ["nginx", "-g", "daemon off;"]