Groom wizard steps 1-15: critique/harden/polish pass

- [P0] CrematoriumStep: Fix <option> → <MenuItem> in priority select
- [P1] All form steps: Add aria-busy={loading} + loading guard on submit
- [P1] Error messages: Replace color="error" (red) with copper
  (var(--fa-color-text-brand)) across ProvidersStep, PackagesStep,
  VenueStep, CrematoriumStep, CemeteryStep, CoffinsStep, PaymentStep
- [P2] IntroStep: "Has the person died?" → "Has this person passed away?"
- [P2] DateTimeStep: "About the person who died" → "who has passed"
- [P2] ProvidersStep: "Showing results from X" → "X providers found"
- [P2] Empty states: Add guidance text for ProvidersStep, PackagesStep,
  VenueStep, CoffinsStep empty results

Steps 4, 13, 15 passed with no issues.

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

src/components/pages/VenueStep/VenueStep.tsx

@@ -207,9 +207,10 @@ export const VenueStep: React.FC<VenueStepProps> = ({
       <Box
         component="form"
         noValidate
+        aria-busy={loading}
         onSubmit={(e: React.FormEvent) => {
           e.preventDefault();
-          onContinue();
+          if (!loading) onContinue();
         }}
       >
         {/* ─── Search + Filters ─── */}
@@ -276,11 +277,26 @@ export const VenueStep: React.FC<VenueStepProps> = ({
               }
             />
           ))}
+
+          {venues.length === 0 && (
+            <Box sx={{ py: 6, textAlign: 'center' }}>
+              <Typography variant="body1" color="text.secondary" sx={{ mb: 1 }}>
+                No venues found in this area.
+              </Typography>
+              <Typography variant="body2" color="text.secondary">
+                Try adjusting your search or clearing filters.
+              </Typography>
+            </Box>
+          )}
         </Box>
 
         {/* Validation error */}
         {errors?.selectedVenueId && (
-          <Typography variant="body2" color="error" sx={{ mb: 2 }} role="alert">
+          <Typography
+            variant="body2"
+            sx={{ mb: 2, color: 'var(--fa-color-text-brand)' }}
+            role="alert"
+          >
             {errors.selectedVenueId}
           </Typography>
         )}