Add applicationId to syncableEntity and fix syncApp deletion (#15170)

## Context
- All flatEntity should extend SyncableEntity
- SyncableEntity should now have applicationId and application relation
- Fix syncApp deletion, should now properly use migration v2 to delete
syncable entities

packages/twenty-server/src/engine/metadata-modules/cron-trigger/entities/cron-trigger.entity.ts

@@ -25,7 +25,10 @@ export const CRON_TRIGGER_ENTITY_RELATION_PROPERTIES = [
 
 @Entity({ name: 'cronTrigger', schema: 'core' })
 @Index('IDX_CRON_TRIGGER_WORKSPACE_ID', ['workspaceId'])
-export class CronTrigger extends SyncableEntity {
+export class CronTrigger
+  extends SyncableEntity
+  implements Required<CronTrigger>
+{
   @PrimaryGeneratedColumn('uuid')
   id: string;