Adding initial Korean translation

[systil3]

Overview

Adds an initial Korean (ISO 639-1: ko) translation for Open Library.
Korean is spoken by approximately 80 million people worldwide, including large communities in South Korea, North America, etc. This PR creates openlibrary/i18n/ko/messages.po with translations covering the whole UI element with EN including core features : account management, borrowing, book editing, navigation, and notifications. This also modifies get_supported_languages() of openlibrary/code.py as adding one line to apply Korean mapping.
This contribution aims to make Open Library more accessible to Korean-speaking users.

Technical

All msgid strings were translated to natural, commonly-used Korean.
Since Korean does not grammatically distinguish singular from plural in the same way English does, we set all plural msgstr entries to use index [0] only.
Technical terms or proper nouns without established Korean equivalents (e.g. "Internet Archive", "eBook", "ISBN", "reCAPTCHA", "Adobe Digital Editions") were kept in their original form exceptionally.

Testing

As indicated in the internationalization section of the open library docs, you can build the modifications using the line docker compose run --rm -uroot home make i18n and validate them using the line docker compose exec -uroot web ./scripts/i18n-messages validate ko.

Screenshot

Stakeholders

@gladmanhh : helped modify line around 5800 ~ 8700 of messages.po
@hajicastle : helped line 2900~5800

[Copilot]

Copilot wasn't able to review any files in this pull request.

[mekarpeles]

Thank you for contributing, @systil3! Welcome to Open Library — this appears to be your first contribution to the project.

🤖 Copilot has been assigned for an initial review.

This PR has no linked issue, so it will go through triage before a reviewer is assigned. Triage runs on Mondays and Fridays. There are currently 66 open non-draft PRs in the queue ahead of yours.

Possible improvements for this PR

• No linked issue — this is a substantial change. If there is an existing issue tracking Korean localization, please link it with a #NNN reference in the PR body. If there isn't one, consider opening one so the team can track and triage it.

PR triage checklist (maintainers / Pam)

• PR description — not empty; explains what the change does and how to verify it
• References an issue — PR body contains a #NNN reference
  • Linked issue is triaged — has a Priority: * label (not just Needs: Triage)
  • Linked issue is assigned — has at least one assignee
• Commit history clean — no WIP/fixup/conflict noise; commit messages are meaningful
• CI passing — no failing check-runs
• Test cases present — if the change touches substantive logic, test coverage exists or is explained
• Proof of testing — PR body includes a description of what was tested, a screenshot, or a video

Note

This comment was automatically generated by Pam, Open Library's Project AI Manager, on behalf of @mekarpeles. Pam is designed to provide status visibility, perform basic project management functions and relevant codebase research, and provide actionable feedback so contributors aren't left waiting.