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/page-layout-widget/dtos/fields-configuration.dto.ts

@@ -7,7 +7,10 @@ import {
   IsOptional,
   IsUUID,
 } from 'class-validator';
-import { type FieldsConfiguration } from 'twenty-shared/types';
+import {
+  type FieldsConfiguration,
+  type SerializedRelation,
+} from 'twenty-shared/types';
 
 import { WidgetConfigurationType } from 'src/engine/metadata-modules/page-layout-widget/enums/widget-configuration-type.type';
 
@@ -21,7 +24,7 @@ export class FieldsConfigurationDTO implements FieldsConfiguration {
   @Field(() => String, { nullable: true })
   @IsOptional()
   @IsUUID()
-  viewId: string | null;
+  viewId: SerializedRelation | null;
 
   @Field(() => Boolean, { nullable: true })
   @IsOptional()