Reset Tab Page Layout (#19453)

## Context
- Add "Reset to default" for page layout tabs and widgets — backend
mutation resets overrides, reactivates deactivated children, and deletes
custom children
- Fix override write bug where mutating an overridable property (e.g.
widget title) on a standard-app entity incorrectly overwrote the base
column instead of writing to the overrides JSONB —
PageLayoutUpdateService now uses resolveFlatEntityOverridableProperties
for accurate diffing and routes properties through
sanitizeOverridableEntityInput
- Deprecate isOverridden - We need more time to think about this
feature. Currently this adds too much complexity for a very small
benefit



https://github.com/user-attachments/assets/a84546c8-1e15-4d9e-a489-0825cf8b8ed2

packages/twenty-front/src/modules/page-layout/utils/createDefaultFrontComponentWidget.ts

@@ -34,7 +34,6 @@ export const createDefaultFrontComponentWidget = (
       columnSpan: gridPosition.columnSpan,
     },
     objectMetadataId: null,
-    isOverridden: false,
     createdAt: new Date().toISOString(),
     updatedAt: new Date().toISOString(),
     deletedAt: null,