- Luckysheet modal: 8-direction resize handles (edge + corner), title bar drag-to-move
- First drag/resize converts from flex-centered to absolute positioning
- Minimize/close reset to centered state on reopen
- New xlsx-viewer.html: standalone Luckysheet page for opening xlsx in separate window
- Added "↗ 새 창" button on xlsx cards to open viewer in a resizable popup window
- Viewer shares session cookies so auth works transparently
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
