Native <select> chevrons render at varying offsets across browsers.
Replaced them with `appearance-none` + an absolute-positioned
chevron-down Icon at right-4 (16px) so the gap between the chevron
and the right border is consistent. Applied to RegisterPage's
salutation select and ShippingStep's shipping/billing country selects.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
4ed021280a
