Fix author attachment field (#15065)

# Migrate Attachment Author to CreatedBy Field

**Twill Task**: https://twill.ai/twentyhq/ENG/tasks/7

## Summary

This PR implements a migration to transition the `Attachment` object
from using an `author` relation field to using the standard `createdBy`
field, addressing issue
https://github.com/twentyhq/core-team-issues/issues/1594.

## Changes

- **Added migration command**
(`1-8-migrate-attachment-author-to-created-by.command.ts`):
- Migrates existing attachment data to use `createdBy` instead of
`author`
- Ensures data integrity during the transition to the standard field
pattern

- **Updated Attachment workspace entity**:
  - Added `createdBy` relation field to the `Attachment` standard object
  - Registered new field ID in `standard-field-ids.ts` constants

- **Integrated migration into upgrade pipeline**:
  - Added migration module for version 1.8
  - Registered in the main upgrade version command module

This change aligns the `Attachment` object with Twenty's standard field
conventions by using the built-in `createdBy` field instead of a custom
`author` field.

---

Fixes https://github.com/twentyhq/core-team-issues/issues/1594

---------

Co-authored-by: Twill <agent@twill.ai>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Félix Malfait <felix.malfait@gmail.com>
Co-authored-by: Félix Malfait <felix@twenty.com>

packages/twenty-server/src/engine/core-modules/health/indicators/__tests__/worker.health.spec.ts

@@ -35,6 +35,7 @@ describe('WorkerHealthIndicator', () => {
 
     const mockRedisService = {
       getClient: () => mockRedis,
+      getQueueClient: () => mockRedis,
     } as unknown as RedisClientService;
 
     healthIndicatorService = {