fix: make subtitle optional for custom sections

  Remove required validation for subtitle field in custom section
  forms.
  Title remains required.

Author: jwalterss

src/curated-corpus/components/CustomSectionForm/CustomSectionForm.tsx

@@ -82,8 +82,7 @@ export const CustomSectionForm: React.FC<CustomSectionFormProps> = ({
               <Field
                 as={TextField}
                 name="subtitle"
-                label="Subtitle"
-                required
+                label="Subtitle (Optional)"
                 fullWidth
                 multiline
                 rows={2}

src/curated-corpus/components/CustomSectionForm/CustomSectionForm.validation.ts

@@ -24,7 +24,6 @@ export const getValidationSchema = (isEditMode: boolean = false) => {
     subtitle: yup
       .string()
       .trim()
-      .required('Subtitle is required')
       .max(500, 'Subtitle cannot exceed 500 characters'),
 
     heroTitle: yup
@@ -95,10 +94,6 @@ export const validateForm = (
     errors.title = 'Title is required';
   }
 
-  if (!formData.subtitle.trim()) {
-    errors.subtitle = 'Subtitle is required';
-  }
-
   if (!formData.startDate) {
     errors.startDate = 'Start date is required';
   } else if (formData.startDate < today) {

src/curated-corpus/components/EditCustomSectionModal/EditCustomSectionModal.test.tsx

@@ -87,9 +87,8 @@ describe('EditCustomSectionModal', () => {
       </MockedProvider>,
     );
 
-    // Check if form text labels are rendered (from CustomSectionFormConnector)
-    expect(screen.getByText('Title')).toBeInTheDocument();
-    expect(screen.getByText('Subtitle')).toBeInTheDocument();
+    // Check if form is rendered - looking for start date label
+    expect(screen.getByText('Start Date')).toBeInTheDocument();
   });
 
   it('should populate form with section data', () => {