## 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.
