fix: show empty cell instead of 'Not shared' for soft-deleted related records (#20260)

## Summary

Fixes #20076 (supersedes #20250)

When a related record is soft-deleted, the frontend displays "Not
shared" (lock icon) because it sees a populated FK but a null relation
object. This is misleading -- the record was deleted, not
permission-restricted.

**Backend fix** (`process-nested-relations-v2.helper.ts`):
- For MANY_TO_ONE relations, widen the relation query with
`.withDeleted()` and include `deletedAt` in the select
- In `assignRelationResults`, if the matched record has `deletedAt` set,
nullify both the FK and the relation object in the API response
- Records filtered by RLS are still not returned (even with
`withDeleted()`), so they correctly continue to show "Not shared"
- Strip `deletedAt` from relation results before returning to the client

**Frontend fix** (`RelationFromManyFieldDisplay.tsx`):
- For ONE_TO_MANY junction relations, return `null` instead of
`<ForbiddenFieldDisplay />` when junction records exist but target
records are unavailable

### Three cases now handled correctly:

| Scenario | FK in response | Relation object | Frontend display |
|---|---|---|---|
| **Live record** | `"abc"` | `{ id: "abc", ... }` | Record chip |
| **Soft-deleted record** | `null` | `null` | Empty cell |
| **RLS-hidden record** | `"abc"` | `null` | "Not shared" |

## Test plan

- [ ] Create a record with a MANY_TO_ONE relation (e.g., a person linked
to a company)
- [ ] Soft-delete the related record (the company)
- [ ] Verify the relation field shows an empty cell, not "Not shared"
- [ ] Restore the related record and verify the relation reappears
- [ ] Verify that RLS-hidden relations still show "Not shared"

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

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

packages/twenty-front/src/modules/object-record/record-field/ui/meta-types/display/components/RelationFromManyFieldDisplay.tsx

@@ -10,7 +10,6 @@ import { isActivityTargetField } from '@/object-record/record-field-list/utils/c
 import { FieldContext } from '@/object-record/record-field/ui/contexts/FieldContext';
 import { useFieldFocus } from '@/object-record/record-field/ui/hooks/useFieldFocus';
 import { useRelationFromManyFieldDisplay } from '@/object-record/record-field/ui/meta-types/hooks/useRelationFromManyFieldDisplay';
-import { ForbiddenFieldDisplay } from '@/object-record/record-field/ui/meta-types/display/components/ForbiddenFieldDisplay';
 import { extractTargetRecordsFromJunction } from '@/object-record/record-field/ui/utils/junction/extractTargetRecordsFromJunction';
 import { getJunctionConfig } from '@/object-record/record-field/ui/utils/junction/getJunctionConfig';
 import { hasJunctionConfig } from '@/object-record/record-field/ui/utils/junction/hasJunctionConfig';
@@ -147,7 +146,7 @@ export const RelationFromManyFieldDisplay = () => {
       .filter(isDefined);
 
     if (fieldValue.some(isDefined) && targetRecordsWithMetadata.length === 0) {
-      return <ForbiddenFieldDisplay />;
+      return null;
     }
 
     return (