style(ui): design polish + replace CUI badge with +RO/−RO
6 design review fixes: diff summary badge in modal header, PF indicator,
eFactura risk icon (octagon vs triangle for colorblind), aria labels,
extract .denom-mismatch CSS class, remove dead .addr-table CSS.
Replace vague "Corectat" badge with directional +RO (green, prefix added)
or −RO (orange, prefix removed). Kit items show "Kit" badge instead of
price match dot. Cache-bust shared.js v24, style.css v31.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>