## Summary
Fix shift+click range selection not properly deselecting assets when
selecting a smaller range, and improve selection performance.
## Changes
- **Bug Fix**: Shift+click now replaces selection with the new range
instead of combining with existing selection
- **Performance**: Remove unnecessary `.every()` check in `setSelection`
(O(n) → O(1))
- **Tests**: Add 23 unit tests for asset selection logic
## Test Plan
- [x] Click 1st asset → only 1st selected
- [x] Shift+click 3rd asset → items 1-3 selected
- [x] Shift+click 1st asset → only 1st selected (was broken, now fixed)
- [x] All 23 new unit tests pass
🤖 Generated with [Claude Code](https://claude.com/claude-code)
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8396-bugfix-Fix-shift-click-deselection-in-asset-panel-2f76d73d3650814ca060d1e6a40cf6d4)
by [Unito](https://www.unito.io)
