chore: frontend dead code removal and naming cleanup (#18690)

## Summary

- **Delete 10 unused files**: 7 hooks (`useWorkflowRunUnsafe`,
`useGetViewById`, `useCreateViewFieldGroup`, `useDeleteViewFieldGroup`,
`useUpdateViewFieldGroup`, `useCreateManyViewFieldGroups`,
`useMoveViewColumns` + test), 1 component (`SettingsSummaryCard`), 1
utility (`createEventContext`)
- **Rename `objectMetadataItemsState` → `objectMetadataItemsSelector`**
across ~85 files to accurately reflect it is a derived selector (via
`createAtomSelector`), not a base Jotai atom

## Details

### Dead code removed

| Type | Name | Reason |
|------|------|--------|
| Hook | `useWorkflowRunUnsafe` | Never imported — duplicate of
`useWorkflowRun` without schema validation |
| Hook | `useGetViewById` | Never imported — `useViewById` is used
instead |
| Hook | `useCreateViewFieldGroup` | Never imported — CRUD done via
`usePerformViewFieldGroupAPIPersist` |
| Hook | `useDeleteViewFieldGroup` | Same as above |
| Hook | `useUpdateViewFieldGroup` | Same as above |
| Hook | `useCreateManyViewFieldGroups` | Same as above |
| Hook | `useMoveViewColumns` | Only imported by its own test — no
production usage |
| Component | `SettingsSummaryCard` | Never imported anywhere |
| Utility | `createEventContext` | Never imported anywhere |

### Rename

`objectMetadataItemsState` is created via `createAtomSelector` (it
derives from `objectMetadataItemsWithFieldsSelector`), so naming it
`*State` is misleading. Renamed to `objectMetadataItemsSelector` for
consistency with sibling selectors like
`objectMetadataItemsByNamePluralMapSelector`.

packages/twenty-front/src/modules/blocknote-editor/blocks/MentionInlineContent.tsx

@@ -1,5 +1,5 @@
 import { MentionRecordChip } from '@/mention/components/MentionRecordChip';
-import { objectMetadataItemsState } from '@/object-metadata/states/objectMetadataItemsState';
+import { objectMetadataItemsSelector } from '@/object-metadata/states/objectMetadataItemsSelector';
 import { RecordChip } from '@/object-record/components/RecordChip';
 import { useFindOneRecord } from '@/object-record/hooks/useFindOneRecord';
 import { createReactInlineContentSpec } from '@blocknote/react';
@@ -32,7 +32,7 @@ const LegacyMentionRenderer = ({
   recordId: string;
   objectMetadataId: string;
 }) => {
-  const objectMetadataItems = useAtomStateValue(objectMetadataItemsState);
+  const objectMetadataItems = useAtomStateValue(objectMetadataItemsSelector);
 
   const objectMetadataItem = objectMetadataItems.find(
     (item) => item.id === objectMetadataId,