feat(dashboard): improve Korean transl and add missing keys (#13081)

## Summary
- Improved Korean translations with natural terms for e-commerce context
- Applied consistent translations throughout the admin interface
- Added all missing required keys for i18n validation

## Changes
- Used appropriate e-commerce terms: "재고 키트" → "구성 상품", "이행" → "주문 처리/배송 준비"
- Applied consistent translation: "항목" → "상품" throughout the file
- Distinguished shipping states: "markAsShipped" (발송 완료), "markAsDelivered" (배송 완료)
- Added missing required keys for products, inventory, orders, taxRegions, and promotions
- All i18n validations now pass

## Test plan
- [x] Run `yarn i18n:validate ko.json` - passes validation
- [x] Verify translations are contextually appropriate for e-commerce
- [x] Ensure consistency across all admin interface sections

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: William Bouchard <46496014+willbouch@users.noreply.github.com>

.changeset/mean-ties-act.md

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+feat(dashboard): improve Korean transl and add missing keys