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/command-menu-item/engine-command/record/multiple-records/components/ExportMultipleRecordsCommand.tsx

@@ -2,7 +2,7 @@ import { HeadlessEngineCommandWrapperEffect } from '@/command-menu-item/engine-c
 import { useMountedEngineCommandContext } from '@/command-menu-item/engine-command/hooks/useMountedEngineCommandContext';
 import { EngineCommandComponentInstanceContext } from '@/command-menu-item/engine-command/states/contexts/EngineCommandComponentInstanceContext';
 import { commandMenuItemProgressFamilyState } from '@/command-menu-item/states/commandMenuItemProgressFamilyState';
-import { type ObjectMetadataItem } from '@/object-metadata/types/ObjectMetadataItem';
+import { type EnrichedObjectMetadataItem } from '@/object-metadata/types/EnrichedObjectMetadataItem';
 import { useRecordIndexExportRecords } from '@/object-record/record-index/export/hooks/useRecordIndexExportRecords';
 import { useAvailableComponentInstanceIdOrThrow } from '@/ui/utilities/state/component-state/hooks/useAvailableComponentInstanceIdOrThrow';
 import { useSetAtomFamilyState } from '@/ui/utilities/state/jotai/hooks/useSetAtomFamilyState';
@@ -15,7 +15,7 @@ const ExportMultipleRecordsCommandContent = ({
   recordIndexId,
   setCommandMenuItemProgress,
 }: {
-  objectMetadataItem: ObjectMetadataItem;
+  objectMetadataItem: EnrichedObjectMetadataItem;
   recordIndexId: string;
   setCommandMenuItemProgress: (value: number | undefined) => void;
 }) => {

packages/twenty-front/src/modules/command-menu-item/engine-command/types/MountedEngineCommandContext.ts

@@ -1,5 +1,5 @@
 import { type ContextStoreTargetedRecordsRule } from '@/context-store/states/contextStoreTargetedRecordsRuleComponentState';
-import { type ObjectMetadataItem } from '@/object-metadata/types/ObjectMetadataItem';
+import { type EnrichedObjectMetadataItem } from '@/object-metadata/types/EnrichedObjectMetadataItem';
 import { type ObjectRecord } from '@/object-record/types/ObjectRecord';
 import {
   type Nullable,
@@ -10,7 +10,7 @@ import { type EngineComponentKey } from '~/generated-metadata/graphql';
 export type MountedEngineCommandState = {
   engineComponentKey: EngineComponentKey;
   contextStoreInstanceId: string;
-  objectMetadataItem: Nullable<ObjectMetadataItem>;
+  objectMetadataItem: Nullable<EnrichedObjectMetadataItem>;
   currentViewId: Nullable<string>;
   recordIndexId: Nullable<string>;
   targetedRecordsRule: ContextStoreTargetedRecordsRule;