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/views/utils/mapColumnDefinitionToViewField.ts

@@ -12,7 +12,6 @@ export const mapColumnDefinitionsToViewFields = (
     position: columnDefinition.position,
     size: columnDefinition.size,
     isVisible: columnDefinition.isVisible ?? true,
-    isOverridden: false,
     definition: columnDefinition,
   }));
 };