VenueServicesStep page + AddOnOption price colour fix

- New VenueServicesStep (step 7c): venue-specific service toggles
  with compact venue card, availability notices, AddOnOption toggles
  with "View more" for long descriptions, conditional tally total
- AddOnOption: price colour changed from text.secondary to primary
  (copper) for consistency with all other price displays in the system
- 5 stories: Default, WithNotice, PrePlanning, WithSelections, Minimal
- Component registry updated with VenueDetailStep + VenueServicesStep

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/molecules/AddOnOption/AddOnOption.tsx

@@ -142,7 +142,7 @@ export const AddOnOption = React.forwardRef<HTMLDivElement, AddOnOptionProps>(
 
         {/* Price — tucks directly under heading */}
         {price != null && (
-          <Typography variant="body2" color="text.secondary">
+          <Typography variant="body2" color="primary">
             ${price.toLocaleString('en-AU')}
           </Typography>
         )}