Add objectRecordCounts query to /metadata endpoint (#18054)

## Summary

- Adds an `objectRecordCounts` query on the `/metadata` GraphQL endpoint
that returns approximate record counts for all objects in the workspace
- Uses PostgreSQL's `pg_class.reltuples` catalog stats — a single
instant query instead of N `COUNT(*)` table scans
- Replaces the previous `CombinedFindManyRecords` approach which hit the
server's 20 root resolver limit and silently showed 0 for all counts on
the settings Data Model page

### Server
- `ObjectRecordCountDTO` — GraphQL type with `objectNamePlural` and
`totalCount`
- `ObjectRecordCountService` — reads `pg_class` catalog for the
workspace schema
- Query added to `ObjectMetadataResolver` with `@MetadataResolver()` +
`NoPermissionGuard`

### Frontend
- `OBJECT_RECORD_COUNTS` query added to
`object-metadata/graphql/queries.ts`
- `useCombinedGetTotalCount` simplified to a zero-argument hook using
the new query
- `SettingsObjectTable` simplified to a single hook call

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

packages/twenty-server/src/engine/metadata-modules/object-metadata/dtos/object-record-count.dto.ts

@@ -0,0 +1,10 @@
+import { Field, Int, ObjectType } from '@nestjs/graphql';
+
+@ObjectType('ObjectRecordCount')
+export class ObjectRecordCountDTO {
+  @Field(() => String)
+  objectNamePlural: string;
+
+  @Field(() => Int)
+  totalCount: number;
+}