fix: update custom fields to fix "Error parsing request body into JSON"

The `customFields` param expects an array of objects where each object
has 2 properties: id and value. This fix ensures the current page is
passed in the `value` property.

src/lib/stores/feedback.ts

@@ -133,7 +133,7 @@ function createFeedbackStore() {
                     // billingPlan,
                     firstname: name || 'Unknown',
                     customFields: [
-                        { id: '47364', currentPage },
+                        { id: '47364', value: currentPage },
                         ...(value ? [{ id: '40655', value }] : [])
                     ],
                     metaFields: {