Migrate noteTarget and taskTarget to Morph. (#17476)

This PR migrates `noteTarget` and `taskTarget` to morph relations behind
separate feature flags, following the Attachment/TimelineActivity
pattern.

It introduces the `IS_NOTE_TARGET_MIGRATED` and
`IS_TASK_TARGET_MIGRATED` flags, updates standard field metadata and
indexes to use morph relations, and adds two **1.17 workspace
migrations** that:
- rename `noteTarget.*Id` / `taskTarget.*Id` columns to `target*Id`
- convert the corresponding field metadata to `MORPH_RELATION` with a
shared `morphId`

On the frontend, note/task target read and write paths switch to
`target*Id` when the respective flag is enabled. Deleted targets are
filtered on reload to prevent reappearing relations.

packages/twenty-front/src/modules/activities/utils/getActivityTargetFieldNameForObject.ts

@@ -1,3 +1,4 @@
+import { getActivityTargetObjectFieldIdName } from '@/activities/utils/getActivityTargetObjectFieldIdName';
 import { CoreObjectNameSingular } from '@/object-metadata/types/CoreObjectNameSingular';
 import { type ObjectMetadataItem } from '@/object-metadata/types/ObjectMetadataItem';
 import { isDefined } from 'twenty-shared/utils';
@@ -8,12 +9,14 @@ type GetActivityTargetFieldNameForObjectArgs = {
     | CoreObjectNameSingular.Task;
   targetObjectMetadataId: string;
   objectMetadataItems: ObjectMetadataItem[];
+  isMorphRelation?: boolean;
 };
 
 export const getActivityTargetFieldNameForObject = ({
   activityObjectNameSingular,
   targetObjectMetadataId,
   objectMetadataItems,
+  isMorphRelation = false,
 }: GetActivityTargetFieldNameForObjectArgs): string | undefined => {
   const activityTargetObjectNameSingular =
     activityObjectNameSingular === CoreObjectNameSingular.Task
@@ -29,10 +32,21 @@ export const getActivityTargetFieldNameForObject = ({
     return undefined;
   }
 
-  const targetField = activityTargetObjectMetadata.fields.find(
-    (field) =>
-      field.relation?.targetObjectMetadata.id === targetObjectMetadataId,
+  const targetObjectMetadataItem = objectMetadataItems.find(
+    (objectMetadataItem) => objectMetadataItem.id === targetObjectMetadataId,
   );
 
-  return targetField?.name;
+  if (isMorphRelation && isDefined(targetObjectMetadataItem)) {
+    const fieldIdName = getActivityTargetObjectFieldIdName({
+      nameSingular: targetObjectMetadataItem.nameSingular,
+      isMorphRelation: true,
+    });
+
+    return fieldIdName.replace(/Id$/, '');
+  }
+
+  return activityTargetObjectMetadata.fields.find(
+    (field) =>
+      field.relation?.targetObjectMetadata.id === targetObjectMetadataId,
+  )?.name;
 };