Fix duplicate Fields widget (#19696)

## Context
Tab duplication was broken after the view creation logic was deferred
and moved to the FE.

- Duplicating a tab or a FIELDS widget now produces a fully independent
copy: new view, new view field groups, new view fields — all with fresh
IDs — while preserving any unsaved edits
  from the source widget.
- Removed the backend auto-seed of default view fields / view field
groups in ViewService.createOne for FIELDS_WIDGET views. The frontend
always sends the complete layout via
upsertFieldsWidget, so the auto-seed was both redundant and the source
of potential bugs.
- Extracted a shared useDuplicateFieldsWidgetForPageLayout hook used by
both tab and widget duplication paths, plus a small
useCloneViewInMetadataStore helper that clones the FlatView
in the metadata store and returns the copied flat view fields/groups for
the caller.

packages/twenty-server/src/engine/metadata-modules/page-layout/services/page-layout-update.service.ts

@@ -174,6 +174,7 @@ export class PageLayoutUpdateService {
       });
 
     const orphanedViewIds = this.collectOrphanedViewIdsFromRemovedWidgets({
+      widgetsToCreate,
       widgetsToUpdate,
       widgetsToDelete,
       tabsToUpdate,
@@ -868,12 +869,14 @@ export class PageLayoutUpdateService {
   }
 
   private collectOrphanedViewIdsFromRemovedWidgets({
+    widgetsToCreate,
     widgetsToUpdate,
     widgetsToDelete,
     tabsToUpdate,
     tabsToDelete,
     flatPageLayoutWidgetMaps,
   }: {
+    widgetsToCreate: FlatPageLayoutWidget[];
     widgetsToUpdate: FlatPageLayoutWidget[];
     widgetsToDelete: FlatPageLayoutWidget[];
     tabsToUpdate: FlatPageLayoutTab[];
@@ -934,6 +937,14 @@ export class PageLayoutUpdateService {
       }
     }
 
+    for (const widget of widgetsToCreate) {
+      const viewId = this.getViewIdFromFieldsWidget(widget);
+
+      if (isDefined(viewId)) {
+        viewIdsToDelete.delete(viewId);
+      }
+    }
+
     return [...viewIdsToDelete];
   }