Translation tracker: auto close issue on PR merged and closed

[aashishpanthi]

Summary

The translation tracker opens a GitHub issue for every outdated or missing translation. Until now, those issues stayed open after the translation actually landed, so maintainers had to close them by hand and there was backlog.

This adds a translation-auto-close.yml workflow that runs when a PR touching translated content is merged. It works out which tracker issues the PR resolves, marks off the languages that were translated, and closes each issue once nothing is left to translate.

Addresses #1404.

How an issue is found

Relying on Resolves #123 did not worked well with real contributors: most translation PRs either use no linking keyword or mention the issue somewhere other than the body. So any #123 is treated as a candidate, and it is looked for in:

• the PR title and body
• conversation comments and review comments (maintainers routinely write "this handles #123" during review)
• issues that cross-reference the PR from their own thread
• pasted https://github.com/<owner>/<repo>/issues/123 links

Also, comments written by bots are ignored, so the tracker's own automation cannot feed itself.

How false positives are avoided

Matching every #123 is deliberately greedy, so candidates are filtered:

• fenced code blocks and inline code spans are stripped first, which removes most hex colors and code samples
• owner/repo#123 cross-repo references and #123abc are not matched; numbers are capped at six digits
• the PR's own number is skipped
• each remaining candidate must exist, must not be a pull request, and must carry the needs translation label

How an issue is updated

Which languages a PR translated is derived from its changed file paths, for example src/content/examples/es/... means Spanish. For each such language, the action removes the lang-<code> label and strikes that language's line in the issue body. The issue is closed only when no lang-* labels are left.

One tracker issue often covers several languages for the same English file, which creates a wrinkle: GitHub closes an issue natively the instant a PR saying Fixes #123 is merged, even when only one of four languages was done. The action detects this and reopens the issue, leaving a comment naming the languages still working.

Testing

npm run test:auto-close runs the flow against a mocked GitHub API and covers: keyword-free references, the reopen path, comment-sourced references, bot filtering, cross-references, noise rejection, referenced pull requests, and PRs with no translation files.