feat: rename to paperspec and add the website

- Rename manuspec to paperspec everywhere outside pixi.toml: prose, the
  tools, provenance tool names and the fixture key derivations, so every
  fixture and vector is rebuilt.
- Move the namespace addresses under the site, mirroring the repository:
  schema $id https://paperspec.scient.ing/schemas/<file>, the JSON-LD
  context https://paperspec.scient.ing/context/scienting-1.jsonld, and
  term IRIs https://paperspec.scient.ing/vocab#<term>. Format
  identifiers (scienting-*) and URNs (urn:scienting:) are unchanged.
- tools/site.py (standard library only) builds _site/: every file of the
  repository at its own path, each Markdown file rendered as a page with
  sidebar navigation, heading anchors matching the forge's, folder
  listings, a vocabulary page for the context's IRIs, a heading search
  and a 404 page; light and dark themes.
- check.py builds the site and checks that every Markdown file has a
  page, every internal link and fragment resolves, no Markdown is left
  unrendered, and every $id, the context address and the vocabulary IRIs
  are files of the site.
- deploy/: a Caddyfile with the media types and CORS the data needs, and
  a guide; .gitea/workflows/site.yml builds on main and publishes with
  rsync when the SITE_* secrets are set.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CONTRIBUTING.md

@@ -1,7 +1,7 @@
 # Contributing
 
 This page is for anyone who wants to fix the specification, change a format or add an example.
-Propose a change as a pull request on the repository at <https://git.scient.ing/infra/manuspec>.
+Propose a change as a pull request on the repository at <https://git.scient.ing/infra/paperspec>.
 
 ## What a change needs
 
@@ -40,7 +40,7 @@ Before tagging:
 1. `pixi run check` passes on Linux and macOS, which the workflow in `.gitea/workflows/` runs on every push.
    The check also confirms that every count the prose states (formats, schemas, vectors, broken packages) matches the repository, and that `pixi.toml`, the registries and `tools/build.py` state the same version.
 2. `python3 tools/stress.py` passes with its default seed, and with one or two others.
-3. The JSON-LD context is served at `https://scient.ing/ns/scienting/1.jsonld` and every schema at its `$id` under `https://scient.ing/ns/schemas/`, both as static files; [context/README.md](context/README.md) records whether they resolved last time someone checked.
+3. The website is published from the release ([deploy/](deploy/README.md)), and the JSON-LD context at `https://paperspec.scient.ing/context/scienting-1.jsonld` and a schema at its `$id` both answer with their media types.
    Layers claim to be W3C Web Annotations, and a JSON-LD processor that cannot fetch the context cannot read them.
 4. The decisions that freeze on release are made: enumeration values and format identifiers never change meaning afterwards ([spec/22 §22.5](spec/22-conformance.md#225-stability)), so a name worth changing is changed now.
 5. The CHANGELOG entry describes the release in the terms of the chapters it touches.