i18n: add Korean (ko) translation

[moduvoice]

Korean (ko) translation PR body template

Motivation

This adds Korean (ko) translation support — to help Korean-speaking users use this
open-source project more comfortably in their own language.

한국 사람들의 오픈소스 이용에 도움이 되게 하기 위해서 한글화 작업을 하였습니다.

Changes

• Add web/src/i18n/locales/ko.json with a full Korean translation (1340 keys, 1:1 parity with en.json)
• Register ko in web/src/i18n/config.ts i18next resources
• Add Korean (한국어) to the language switcher in web/src/shared/components/language-switcher.tsx

Testing

• Programmatic key-parity check: en.json and ko.json both have exactly 1340 keys, 0 missing/extra
• Programmatic interpolation/tag check: all {{variable}} placeholders and <1>...</1> style tags match between en.json and ko.json
• pnpm vitest run — 180 files / 609 tests passing
• pnpm typecheck (tsc --noEmit) — clean
• pnpm lint (eslint) — clean
• Manual spot-check of terminology consistency across the file (스킬/에이전트/네임스페이스/거버넌스/승격/즐겨찾기/보관/복원/동결/회수 etc.), confirming consistent usage throughout
• Confirmed the hardcoded bilingual (zh/en) legal-text components (login, terms, privacy, notification-content) are intentionally left untouched, as they are out of scope for this i18n-resource-based translation

[CLAassistant]

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[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[FenjuFu]

CI is approved and running now. One thing left on your side: please sign the CLA (see the license/cla check link) so this can merge once checks are green.

[FenjuFu]

Update after approving CI: besides the CLA, the DCO check fails (commits need Signed-off-by — git rebase --signoff + force-push). The E2E (Real Services) failure may be secret-gated for fork PRs; we'll re-check it once DCO/CLA are sorted.