Translate docs/src/quickstart.md into one or more languages (i18n outreach)

[Metbcy]

Context

bomdrift claims to localize at the docs surface and via the Action's PR-comment markdown — but neither is translated. For adoption in non-English-first engineering orgs, having at least one quickstart translation lowers the bar significantly.

Scope

Translate docs/src/quickstart.md to one or more languages. Suggested first languages (in rough priority order based on pkg.go.dev / npm / PyPI traffic):

• Japanese (docs/src/ja/quickstart.md)
• Simplified Chinese (docs/src/zh-CN/quickstart.md)
• German (docs/src/de/quickstart.md)
• Portuguese (BR) (docs/src/pt-BR/quickstart.md)
• Korean (docs/src/ko/quickstart.md)

Pick whichever language(s) you're a native or near-native speaker in. Don't translate in languages you're not comfortable in — bad localization is worse than no localization.

Acceptance criteria

• At least one new translated quickstart in a language directory under docs/src/<lang>/.
• docs/src/SUMMARY.md updated to expose the translation in the navigation (a sub-section "Translations" or per-language root chapter).
• Code blocks (CLI examples, YAML, etc.) not translated — keep flag names, env vars, config keys verbatim. Translate only narrative text.
• The translation includes a "Last reviewed: vX.Y.Z" footer so future docs changes get a stale-translation signal.

Notes

• Don't translate anything else yet — quickstart is the highest-traffic page; everything else can follow once we know there's demand.
• Don't try to translate the rendered PR comment (output) — that's content + format-string-bound and will diverge from the bomdrift run-time output. Localizing CLI output is a separate (much bigger) ask.

A note on commit signing

main requires verified signatures (the repo ships cosign-signed releases — we hold our own commits to the same bar).

You usually don't need to set up signing as a contributor — when a maintainer merges via "Merge" or "Squash", GitHub auto-signs the resulting commit and your unsigned PR-branch commits are fine. The friendlier path for everyone.

If you'd like your individual commits to land verbatim on main (so your name shows up in git blame), set up local signing once and your PR can be rebase-merged:

git config --global gpg.format ssh
git config --global user.signingkey ~/.ssh/id_ed25519.pub
git config --global commit.gpgsign true

Then add the same SSH public key under GitHub → Settings → SSH and GPG keys → Signing keys.

See CONTRIBUTING.md → Commit signing on main for the full picture. Either way, please don't sweat it — if your PR is otherwise great, the maintainer will pick a merge mode that works.