ConfirmationStep redesign, page tweaks across wizard

- ConfirmationStep: animated SVG tick, "What happens next" warm card,
  bullet-point layout, contactPhone prop, link-based secondary actions
- VenueStep + ProvidersStep: sticky search bar padding fix, off-white
  bg behind card lists
- IntroStep, CemeteryStep, CrematoriumStep, DateTimeStep: add divider
  under subheading for visual separation
- CoffinsStep: h4 heading (matches VenueStep/ProvidersStep list layout),
  sidebar headings h5 → h6

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

src/components/pages/CoffinsStep/CoffinsStep.tsx

@@ -418,12 +418,11 @@ export const CoffinsStep: React.FC<CoffinsStepProps> = ({
     >
       {/* ─── Sidebar (left panel) ─── */}
 
-      {/* Heading */}
-      <Typography variant="display3" component="h1" sx={{ mb: 2 }} tabIndex={-1}>
+      {/* Heading — matches VenueStep / ProvidersStep list layout */}
+      <Typography variant="h4" component="h1" sx={{ mb: 0.5, pt: 2 }} tabIndex={-1}>
         Choose a coffin
       </Typography>
-
-      <Typography variant="body1" color="text.secondary" sx={{ mb: 3 }}>
+      <Typography variant="body2" color="text.secondary" sx={{ mb: 2 }}>
         {isPrePlanning
           ? 'Browse the range to get an idea of styles and pricing.'
           : 'Browse our selection of bespoke designer coffins.'}
@@ -457,7 +456,7 @@ export const CoffinsStep: React.FC<CoffinsStepProps> = ({
       <Divider sx={{ mb: 3 }} />
 
       {/* ─── Categories menu — single-select with expandable subcategories ─── */}
-      <Typography variant="h5" sx={{ mb: 1.5 }}>
+      <Typography variant="h6" sx={{ mb: 1.5 }}>
         Categories
       </Typography>
       <Box component="nav" aria-label="Filter by category" sx={{ mb: 3 }}>
@@ -518,7 +517,7 @@ export const CoffinsStep: React.FC<CoffinsStepProps> = ({
       <Divider sx={{ mb: 3 }} />
 
       {/* ─── Price range slider with editable inputs ─── */}
-      <Typography variant="h5" sx={{ mb: 1.5 }}>
+      <Typography variant="h6" sx={{ mb: 1.5 }}>
         Price
       </Typography>
       <Box sx={{ px: 1, mb: 1.5 }}>
@@ -568,7 +567,7 @@ export const CoffinsStep: React.FC<CoffinsStepProps> = ({
       <Divider sx={{ mb: 3 }} />
 
       {/* ─── Sort by ─── */}
-      <Typography variant="h5" sx={{ mb: 2 }}>
+      <Typography variant="h6" sx={{ mb: 2 }}>
         Sort by
       </Typography>
       <TextField