Close [AI-411](https://linear.app/affine-design/issue/AI-411)
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## Summary by CodeRabbit
- Bug Fixes
- Releasing the mouse now always ends panning, preventing stuck states.
- Actions cancel correctly when you release without dragging.
- Refactor
- More consistent Copilot activation: use right-click or Ctrl (⌘ on Mac)
+ left-click.
- Smoother switching to Copilot with improved drag-state reset and
cleanup.
- Removed automatic restoration of previous selection when activating
Copilot.
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