refactor: Webhooks (#12487)

Closes #12303

### What’s Changed
- Replace auto‐save with explicit Save / Cancel
Webhook forms now use manual “Save” and “Cancel” buttons instead of the
old debounced auto‐save/update.

- Separate “New” and “Detail” routes
Two dedicated paths `/settings/webhooks/new` for creation and
/`settings/webhooks/:webhookId` for editing, making the UX clearer.

- URL hint & normalization
If a user omits the http(s):// scheme, we display a “Will be saved as
https://…” hint and automatically default to HTTPS.

- Centralized validation with Zod
Introduced a `webhookFormSchema` for client‐side URL, operations, and
secret validation.

- Storybook coverage
Added stories for both “New Webhook” and “Webhook Detail”

- Unit tests
Added tests for the new `useWebhookForm` hook

packages/twenty-front/src/testing/graphqlMocks.ts

@@ -671,6 +671,26 @@ export const graphqlMocks = {
         });
       },
     ),
+    graphql.query<GraphQLQuery, { objectRecordId: string }>(
+      'FindOneWebhook',
+      ({ variables: { objectRecordId } }) => {
+        return HttpResponse.json({
+          data: {
+            webhook: {
+              __typename: 'Webhook',
+              id: objectRecordId,
+              createdAt: '2021-08-27T12:00:00Z',
+              updatedAt: '2021-08-27T12:00:00Z',
+              deletedAt: null,
+              targetUrl: 'https://example.com/webhook',
+              description: 'A Sample Description',
+              operations: ['*.created', '*.updated'],
+              secret: 'sample-secret',
+            },
+          },
+        });
+      },
+    ),
     graphql.query('FindManyWorkflows', () => {
       return HttpResponse.json({
         data: workflowQueryResult,