[Minseok Song (skytin1004)]

Purpose

Make the first translation easier to follow and keep visitors on the same guide when switching documentation languages on GitHub Pages. Previously, some examples used invalid CLI/API arguments, and the language selector could reset navigation or request nonexistent per-language sitemaps.

Description

• Clarify provider setup, PowerShell activation, credential-free previews, and the choice between CLI, Python API, and MCP. Update the reviewed Korean onboarding pages and add the Korean first-translation walkthrough.
• Correct CLI/API examples, explain when source changes overwrite manual translation edits, and make the standard Actions example translate and review Markdown before opening a PR.
• Generate language availability from the pages MkDocs actually publishes. Preserve the current guide during language changes and clearly label English fallbacks for unavailable translations.
• Resolve navigation under the GitHub Pages project path, including deep links and Material instant navigation. Keep language alternates in the shared sitemap and prevent requests for nonexistent language-specific sitemaps.
• Add navigation tests and a static artifact check to the documentation build workflow.

Related Issue

None.

Does this introduce a breaking change?

• Yes
• No

No CLI, public API, configuration, or generated translation-output contract changes.

Type of change

• Bugfix
• Feature
• Code style update (e.g., formatting, local variables)
• Refactoring (no functional or API changes)
• Documentation content changes
• Other... Please describe:

Checklist

• I have thoroughly tested my changes: ran focused tests and manually checked the affected documentation navigation.
• All existing tests pass: live API tests were not run; the credential-free suite passed in GitHub CI on Python 3.11, 3.12, 3.13, and 3.14.
• I have added new tests: covered navigation, generated routes, sitemap alternates, and static artifact integrity.
• I have followed the Co-op Translator coding conventions.
• I have documented my changes.

Validation

• 5 Python documentation tests and 8 Node navigation tests passed.
• Documentation tests also skip cleanly when MkDocs is unavailable; the dedicated documentation workflow installs the required dependencies and runs all 5 tests.
• GitHub CI passed on Python 3.11–3.14, including the Python 3.14 requirements check. CodeQL analysis passed.
• Strict MkDocs build passed with the production site URL unchanged.
• The latest PR commit also passed the GitHub documentation workflow, including navigation tests, the strict build, and static artifact validation; deployment was skipped as expected for a PR.
• Static artifact validation passed: 718 routes, assets/script ordering on 8 English/Korean guides, and 731 sitemap entries under /co-op-translator/.
• Edge CUA checks passed against the built files served by a plain static HTTP server at /co-op-translator/: language switching, Korean navigation, labelled English fallback, direct deep links, reload, back/forward, index.html and slashless URLs, and query/fragment behavior. The final session recorded 42 project-path requests with no 4xx/5xx responses.
• Black, Ruff, and git diff --check passed for the changed code.

Additional context

Broader translation regeneration and source-to-translation mapping synchronization are deferred to a follow-up PR using Co-op Translator. This PR includes the reviewed onboarding edits and the navigation fixes needed to serve the currently available pages.

GitHub Pages compatibility was verified locally using the production build configuration and project-path layout. These changes have not been deployed to the public Pages site. An existing Tailwind CDN advisory and the browser's unrelated host-root favicon probe remain outside this change.