scaffold record page layout + fields view when adding an object (#19977)

## Summary

Extends `yarn twenty add` → **Object** so it scaffolds a complete record
page out
of the box:

- A **record-page-fields view** (`<name>-record-page-fields.ts`,
FIELDS_WIDGET)
pre-populated with the `name` field plus the auto-generated default
fields (`createdAt`,
`updatedAt`, `createdBy`, `updatedBy`) — the default-field entries are
emitted as
`generateDefaultFieldUniversalIdentifier({ objectUniversalIdentifier,
fieldName: '...' })`
calls rather than pre-computed UUIDs, so the generated file
double-serves as
documentation for the public util.
- A **record page layout** (`<name>-record-page-layout.ts`) with a Home
tab whose Fields
widget points at the new view (via `viewUniversalIdentifier`), plus a
Timeline tab.
- The companion prompt now covers all three artefacts (was view + nav
menu item).

Fix: Server-side, renames `viewId` → `viewUniversalIdentifier` on the
universal-flat FIELDS
widget configuration so it is consistent with other universal-flat
references. The DB-side
DTO keeps `viewId` (now typed as `SerializedRelation`), and the
conversion utils map
between the two.

<img width="337" height="349" alt="Screenshot 2026-04-22 at 15 40 22"
src="https://github.com/user-attachments/assets/59e36540-1761-46b0-808d-648c68604268"
/>

packages/twenty-server/src/engine/metadata-modules/flat-page-layout-widget/validators/utils/validate-fields-flat-page-layout-widget-for-creation.util.ts

@@ -40,17 +40,23 @@ export const validateFieldsFlatPageLayoutWidgetForCreation = (
     return errors;
   }
 
-  const viewId = (
-    universalConfiguration as { configurationType: string; viewId?: unknown }
-  ).viewId;
+  const viewUniversalIdentifier = (
+    universalConfiguration as {
+      configurationType: string;
+      viewUniversalIdentifier?: unknown;
+    }
+  ).viewUniversalIdentifier;
 
-  if (isDefined(viewId) && viewId !== null) {
-    if (typeof viewId !== 'string' || !uuidValidate(viewId)) {
+  if (isDefined(viewUniversalIdentifier) && viewUniversalIdentifier !== null) {
+    if (
+      typeof viewUniversalIdentifier !== 'string' ||
+      !uuidValidate(viewUniversalIdentifier)
+    ) {
       errors.push({
         code: PageLayoutWidgetExceptionCode.INVALID_PAGE_LAYOUT_WIDGET_DATA,
-        message: t`Invalid viewId for fields widget "${widgetTitle}". Expected a valid UUID`,
-        userFriendlyMessage: msg`Invalid viewId for fields widget`,
-        value: viewId,
+        message: t`Invalid viewUniversalIdentifier for fields widget "${widgetTitle}". Expected a valid UUID`,
+        userFriendlyMessage: msg`Invalid viewUniversalIdentifier for fields widget`,
+        value: viewUniversalIdentifier,
       });
     }
   }