Update Widoco build and deployment workflow

[tmcphillips]

Summary

Build Widoco Docker image from project-maintained Dockerfile and create deployment workflow in trace-vocabularies hub repository.

Changes

• New Dockerfile: version-pinned Widoco 1.4.25, JDK 17, alpine-based
• Use the standard docker run GitHub action
• PR guard — PRs build and generate docs (to catch errors) but only merges to main deploy to Pages
• Separate build, generate, organize, deploy steps for clear logging
• Update actions/checkout to v5 (Node.js 20 deprecated June 2026)
• Add short-name anchors to Widoco HTML output #17 so term-level fragment URIs resolve correctly
• Add custom Widoco sections with links to curated documentation in trace-specification

Steps

• Add widoco/Dockerfile to trace-vocabularies repo
• Create .github/workflows/deploy.yml
• Verify GitHub Pages output after workflow runs

Related

• Create trace-vocabularies repo to serve as hub for TRACE vocabularies #20