CrematoriumStep: add "Decide later" option to witness question

Grief-sensitive third option — users shouldn't feel forced into a
hearse attendance decision during a difficult time. Captures intent
as unresolved so the funeral arranger can follow up.

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

src/components/pages/CrematoriumStep/CrematoriumStep.tsx

@@ -25,7 +25,7 @@ export interface Crematorium {
 /** Form values for the crematorium step */
 export interface CrematoriumStepValues {
   /** Will anyone follow the hearse? (service & cremation only) */
-  attend: 'yes' | 'no' | null;
+  attend: 'yes' | 'no' | 'later' | null;
 }
 
 /** Field-level error messages */
@@ -251,6 +251,7 @@ export const CrematoriumStep: React.FC<CrematoriumStepProps> = ({
               options={[
                 { value: 'yes', label: 'Yes' },
                 { value: 'no', label: 'No' },
+                { value: 'later', label: 'Decide later' },
               ]}
               value={values.attend}
               onChange={(v) =>