v0.1.0

The first release. Everything below is new.

While the version is 0.x the flag surface and the MCP payload shapes may
still change. A change that breaks either will bump the minor version and say
so here.

Added

• Serving a built MkDocs site over HTTP: content-hash ETags, compression done
  once at startup, security headers, a per-path cache policy, directory URLs,
  the project's own 404.html, range requests.
• An MCP server over Streamable HTTP and stdio, with four section-shaped tools
  (search_docs, get_section, get_page, list_pages) and one resource per
  page.
• A BM25 index over sections, weighting heading terms and preserving version
  strings through tokenisation.
• site, mcp and site+mcp modes from one binary.
• -healthcheck and -mcp-probe, so a distroless image with no shell can
  still be probed.
• cmd/anchorcheck, which compares computed anchors against a real built site.
• scripts/release.sh and its parts (test.sh, build.sh, dist.sh,
  image.sh): cross-compiled archives with checksums, a container image, an
  annotated tag and a GitHub release from one command.
• Documentation: SERVING.md (the site half), MCP.md (the agent half),
  ARCHITECTURE.md (how it works inside), DEPLOYMENT.md (Docker, Cloud
  Foundry with both a Docker application and the binary buildpack, and
  Kubernetes), COMPARISON.md (what this replaces and what it costs) and
  RELEASING.md.
• mkdocsgo-example, a companion repository: a complete MkDocs project wired
  to this server, with every deployment manifest filled in.
• The MIT licence, shipped inside every release archive.