feat(i18n): add Korean (ko-KR) translation

[moduvoice]

Add a complete Korean localization for the dashboard:

• Add src/locales/ko-KR.json with all 469 message keys translated
• Register the 한국어 (ko-KR) option in Language.ts, wiring up the antd ko_KR locale and the message catalog

Placeholders (%s, %s1, ...) and inline HTML/EJS markers are preserved, and key order matches en-US.json so yarn generate-locales stays a no-op.

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