Deploy docs site with Hugo via GitHub Actions

[oschwald]

Summary

Migrates the Pages index from Jekyll on gh-pages to a Hugo build that
publishes back onto gh-pages from GitHub Actions. All CSS is now
inlined in the layout template — no external CDN dependencies.

The historical Doxygen output under /doc/vX.Y.Z/ (frozen since 2022)
is preserved untouched by the workflow's keep_files: true, matching
the Terraform comment that calls out the intent of keeping old API doc
links alive.

• Hugo site lives under docs/ on main and mounts README.md as
  the home page
• A small pill nav links from the overview to the Doxygen output at
  /doc/latest/
• .github/workflows/pages.yml builds with mise run build-docs and
  pushes to gh-pages via peaceiris/actions-gh-pages with
  keep_files: true
• No release.sh change needed — this repo's release script doesn't
  publish to gh-pages

Same design as MaxMind-DB PR #221.

For STF-448.

Post-merge steps

1. Verify the live site at https://maxmind.github.io/GeoIP2-dotnet/ and
   a sample /doc/latest/ still loads after the next workflow run
2. In a separate commit on gh-pages, drop the legacy Jekyll source
   files

Pages source stays on gh-pages — no Terraform change for this repo.

Test plan

• mise run build-docs succeeds with no warnings
• Rendered <title>, <h1>, and pill nav are correct
• No static-gh.maxmind.com references in the new site
• Build job passes in CI (push step only runs on main)
• After merge, confirm the workflow pushes successfully to gh-pages
  and /doc/vX.Y.Z/ subtrees are preserved

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request introduces a Hugo-based documentation site for the GeoIP2 .NET API, including a base layout, custom heading anchors, and build tasks in the mise configuration. Feedback includes a suggestion to use a leading slash in the API documentation link for more robust URL resolution, a recommendation to clean up redundant tool versions in the mise.lock file, and a suggestion to externalize hardcoded strings in the layout template to facilitate future internationalization.

[gemini-code-assist]

Using a relative path without a leading slash in relURL can lead to broken links if the site is accessed without a trailing slash (e.g., .../GeoIP2-dotnet). In such cases, the browser may resolve the link relative to the parent directory instead of the site root. Adding a leading slash ensures Hugo prepends the baseURL path correctly, making the link more robust across different entry points.

Suggested change

	<a href="{{ "doc/latest/" | relURL }}">API documentation</a>
	<a href="{{ "/doc/latest/" | relURL }}">API documentation</a>

[gemini-code-assist]

The lockfile now contains multiple versions of node (25.8.0 and 26.1.0) and prettier (3.8.1 and 3.8.3). Since mise.toml specifies latest for these tools, it is cleaner to only lock the single latest version to avoid redundant tool installations in development and CI environments. This can be resolved by running mise lock --force or manually removing the older entries from the lockfile.

[gemini-code-assist]

Several user-facing strings and the document language are hardcoded in the layout template (e.g., lang="en" on line 2, "Overview" on line 200, and "API documentation" on line 201). To support future internationalization (i18n) and improve maintainability, consider moving these to Hugo's i18n files or site parameters.

[oschwald]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a Hugo-based documentation site for the project, including the initial configuration, a base HTML layout with embedded CSS, and custom heading templates. It also updates the project's tool configuration and build tasks to support generating and serving the documentation. The review feedback focuses on improving the documentation's internationalization and responsiveness, specifically suggesting the use of site-configured language codes, the implementation of i18n for navigation strings, and the addition of CSS to ensure images are responsive.

[gemini-code-assist]

The lang attribute is hardcoded to "en". It is better to use the site's configured language code to support potential future internationalization.

Suggested change

	<html lang="en">
	<html lang="{{ .Site.LanguageCode | default "en" }}">

[gemini-code-assist]

The CSS is missing a rule to ensure that images within the content (e.g., from the README) are responsive and do not overflow their container on smaller screens.

      img {
        max-width: 100%;
        height: auto;
      }
    </style>

[gemini-code-assist]

User-facing strings like "Overview" and "API documentation" are hardcoded. Consider using Hugo's i18n features (e.g., the i18n or T function) to make these strings translatable, especially since this is a new documentation setup.