Steps 8-15: consistency pass — subheading, spacing, dividers, Link atom

- CrematoriumStep: body1 subheading, mb:5, section dividers between questions
- CemeteryStep, CoffinDetailsStep, AdditionalServicesStep, SummaryStep: mb:5
- CoffinDetailsStep: body1 subheading
- PaymentStep: mb:5, Link atom for terms links (replaces Box component=a)
- ConfirmationStep: Link atom for phone number

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

src/components/pages/SummaryStep/SummaryStep.tsx

@@ -124,7 +124,7 @@ export const SummaryStep: React.FC<SummaryStepProps> = ({
         Check everything looks right before confirming.
       </Typography>
 
-      <Typography variant="body2" color="text.secondary" sx={{ mb: 4 }}>
+      <Typography variant="body2" color="text.secondary" sx={{ mb: 5 }}>
         You can edit any section by tapping the edit icon.
       </Typography>