feat: add Korean (ko-kr) localization

[formula1092-a11y]

Summary

• Add complete Korean (ko-kr) localization file for Harvester UI Extension
• Translated all 12 top-level sections from en-us.yaml: generic, unsupported, nav, resourceTable, validation, members, asyncButton, dialog, harvester, typeDescription, advancedSettings, typeLabel
• Covers all UI components including VM management, volumes, images, networks, storage, hosts, monitoring, logging, addons, PCI/vGPU/USB devices, load balancers, IP pools, and more

Translation Principles

• YAML keys preserved exactly as in en-us.yaml
• Placeholders ({name}, {count}, etc.), HTML tags, URLs, and ICU MessageFormat patterns kept intact
• Technical terms preserved in English where appropriate: Kubernetes, Namespace, Pod, SSH, VLAN, CIDR, SR-IOV, NTP, etc.
• Common IT terms translated to standard Korean: Virtual Machine → 가상 머신, Snapshot → 스냅샷, Volume → 볼륨, Migration → 마이그레이션, Storage → 스토리지, etc.

PR Checklists

• YAML syntax validated (Python yaml.safe_load)
• All 12 top-level key sections match between en-us.yaml and ko-kr.yaml
• Build test passed (yarn build-pkg harvester)
• ESLint passed (via pre-commit hook)

Related Issue

N/A - New localization contribution

Test

1. Place ko-kr.yaml in pkg/harvester/l10n/
2. Set browser language to Korean (ko-KR)
3. Access Harvester UI through Rancher Dashboard
4. Verify all UI strings display in Korean