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/constants/DefaultWorkflowVersionPageLayout.ts

@@ -32,7 +32,6 @@ export const DEFAULT_WORKFLOW_VERSION_PAGE_LAYOUT: PageLayout = {
       position: 100,
       layoutMode: PageLayoutTabLayoutMode.VERTICAL_LIST,
       pageLayoutId: DEFAULT_WORKFLOW_VERSION_PAGE_LAYOUT_ID,
-      isOverridden: false,
       createdAt: new Date().toISOString(),
       updatedAt: new Date().toISOString(),
       deletedAt: null,
@@ -56,7 +55,6 @@ export const DEFAULT_WORKFLOW_VERSION_PAGE_LAYOUT: PageLayout = {
             configurationType: WidgetConfigurationType.FIELDS,
             viewId: null,
           },
-          isOverridden: false,
           createdAt: new Date().toISOString(),
           updatedAt: new Date().toISOString(),
           deletedAt: null,
@@ -73,7 +71,6 @@ export const DEFAULT_WORKFLOW_VERSION_PAGE_LAYOUT: PageLayout = {
       position: 200,
       layoutMode: PageLayoutTabLayoutMode.CANVAS,
       pageLayoutId: DEFAULT_WORKFLOW_VERSION_PAGE_LAYOUT_ID,
-      isOverridden: false,
       createdAt: new Date().toISOString(),
       updatedAt: new Date().toISOString(),
       deletedAt: null,
@@ -97,7 +94,6 @@ export const DEFAULT_WORKFLOW_VERSION_PAGE_LAYOUT: PageLayout = {
             configurationType: WidgetConfigurationType.FIELDS,
             viewId: null,
           },
-          isOverridden: false,
           createdAt: new Date().toISOString(),
           updatedAt: new Date().toISOString(),
           deletedAt: null,