Add import skill modal that accepts .zip files via drag-and-drop or
file picker, extracts them client-side using fflate, validates structure
and security constraints, then batch uploads via presigned URLs.
- Add fflate dependency for browser-side ZIP decompression
- Create zip-extract.ts with fflate filter API for validation
- Create zip-to-upload-tree.ts for BatchUploadNodeInput tree building
- Create import-skill-modal.tsx with drag-and-drop support
- Lazy-load ImportSkillModal via next/dynamic for bundle optimization
- Add en-US and zh-Hans i18n keys for import modal
ea88bcfbd2