- Add quantity adjustment controls (+ and -) on checkout order summary
- Prevent quantity from going below 1 with disabled minus button at qty=1
- Fix shipping selector not updating by wrapping callback in useCallback
- Shipping option changes now properly update order total
- Totals recalculate reactively when adjusting quantities or shipping
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
