refactor: rename ObjectMetadataItem to EnrichedObjectMetadataItem and clean up metadata flows (#18830)

## Summary

- Renames `ObjectMetadataItem` to `EnrichedObjectMetadataItem` across
the entire frontend (~440 files) to clarify that this type includes
derived fields (`readableFields`, `updatableFields`, nested `fields[]`,
`indexMetadatas[]`) computed at read time from the metadata store
- Creates `splitObjectMetadataGqlResponse` that goes directly from a
GraphQL `ObjectMetadataItemsQuery` response to flat store items
(combining the old
`mapPaginatedObjectMetadataItemsToObjectMetadataItems` +
`splitObjectMetadataItemWithRelated` two-step flow into one call)
- Removes `ObjectMetadataItemWithRelated` type and all "WithRelated"
naming
- Renames `generatedMockObjectMetadataItems` to
`generateTestEnrichedObjectMetadataItemsMock` to make it clear this is
test-only enriched data
- Deletes `useLoadMockedObjectMetadataItems` hook (consolidated into
`useLoadMockedMinimalMetadata`)
- Ensures nothing destined for the metadata store computes
`readableFields`/`updatableFields` (preventing the localStorage bloat
from #18809)

## Type hierarchy (before → after)

**Before:**
```
ObjectMetadataItemsQuery → mapPaginated → ObjectMetadataItemWithRelated → enrich → ObjectMetadataItem
                                        → split → FlatObjectMetadataItem (store)
```

**After:**
```
ObjectMetadataItemsQuery → splitObjectMetadataGqlResponse → FlatObjectMetadataItem (store)
                         → mapPaginated + enrich (tests only) → EnrichedObjectMetadataItem
```

## Test plan

- [x] `npx nx typecheck twenty-front` passes
- [x] `npx nx test twenty-front` passes (767 suites, 4505 tests)
- [x] `npx nx lint twenty-front` passes
- [ ] CI checks pass


Made with [Cursor](https://cursor.com)

packages/twenty-front/src/modules/settings/data-model/utils/__tests__/getFieldPreviewValueFromRecord.test.ts

@@ -1,14 +1,16 @@
 import { type ObjectRecord } from '@/object-record/types/ObjectRecord';
 
-import { generatedMockObjectMetadataItems } from '~/testing/utils/generatedMockObjectMetadataItems';
+import { getTestEnrichedObjectMetadataItemsMock } from '~/testing/utils/getTestEnrichedObjectMetadataItemsMock';
 import { getFieldPreviewValueFromRecord } from '@/settings/data-model/utils/getFieldPreviewValueFromRecord';
-const mockedCompanyObjectMetadataItem = generatedMockObjectMetadataItems.find(
-  (item) => item.nameSingular === 'company',
-);
+const mockedCompanyObjectMetadataItem =
+  getTestEnrichedObjectMetadataItemsMock().find(
+    (item) => item.nameSingular === 'company',
+  );
 
-const mockedPersonObjectMetadataItem = generatedMockObjectMetadataItems.find(
-  (item) => item.nameSingular === 'person',
-);
+const mockedPersonObjectMetadataItem =
+  getTestEnrichedObjectMetadataItemsMock().find(
+    (item) => item.nameSingular === 'person',
+  );
 
 describe('getFieldPreviewValueFromRecord', () => {
   describe('RELATION field', () => {

packages/twenty-front/src/modules/settings/data-model/utils/getConflictingObjectMetadataItem.ts

@@ -1,8 +1,8 @@
-import { type ObjectMetadataItem } from '@/object-metadata/types/ObjectMetadataItem';
+import { type EnrichedObjectMetadataItem } from '@/object-metadata/types/EnrichedObjectMetadataItem';
 import { isDefined } from 'twenty-shared/utils';
 
 type GetConflictingObjectMetadataItemParams = {
-  objectMetadataItems: ObjectMetadataItem[];
+  objectMetadataItems: EnrichedObjectMetadataItem[];
   nameSingular?: string;
   namePlural?: string;
   excludeObjectId?: string;
@@ -13,7 +13,9 @@ export const getConflictingObjectMetadataItem = ({
   nameSingular,
   namePlural,
   excludeObjectId,
-}: GetConflictingObjectMetadataItemParams): ObjectMetadataItem | undefined => {
+}: GetConflictingObjectMetadataItemParams):
+  | EnrichedObjectMetadataItem
+  | undefined => {
   if (!isDefined(nameSingular) && !isDefined(namePlural)) {
     return undefined;
   }

packages/twenty-front/src/modules/settings/data-model/utils/getFieldIdentifierType.ts

@@ -1,11 +1,11 @@
 import { type FieldMetadataItem } from '@/object-metadata/types/FieldMetadataItem';
-import { type ObjectMetadataItem } from '@/object-metadata/types/ObjectMetadataItem';
+import { type EnrichedObjectMetadataItem } from '@/object-metadata/types/EnrichedObjectMetadataItem';
 import { isLabelIdentifierField } from '@/object-metadata/utils/isLabelIdentifierField';
 import { type FieldIdentifierType } from '@/settings/data-model/types/FieldIdentifierType';
 
 export const getFieldIdentifierType = (
   activeFieldMetadatItem: FieldMetadataItem,
-  activeObjectMetadataItem: ObjectMetadataItem,
+  activeObjectMetadataItem: EnrichedObjectMetadataItem,
 ): FieldIdentifierType | undefined => {
   const fieldIsLabelIdentifier = isLabelIdentifierField({
     fieldMetadataItem: activeFieldMetadatItem,