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-client-sdk/src/metadata/generated/schema.graphql

@@ -584,7 +584,7 @@ type ViewField {
   createdAt: DateTime!
   updatedAt: DateTime!
   deletedAt: DateTime
-  isOverridden: Boolean!
+  isOverridden: Boolean @deprecated(reason: "isOverridden is deprecated")
 }
 
 enum AggregateOperations {
@@ -693,7 +693,7 @@ type ViewFieldGroup {
   updatedAt: DateTime!
   deletedAt: DateTime
   viewFields: [ViewField!]!
-  isOverridden: Boolean!
+  isOverridden: Boolean! @deprecated(reason: "isOverridden is deprecated")
 }
 
 type View {
@@ -899,7 +899,7 @@ type PageLayoutWidget {
   createdAt: DateTime!
   updatedAt: DateTime!
   deletedAt: DateTime
-  isOverridden: Boolean!
+  isOverridden: Boolean @deprecated(reason: "isOverridden is deprecated")
 }
 
 enum WidgetType {
@@ -1233,7 +1233,7 @@ type PageLayoutTab {
   createdAt: DateTime!
   updatedAt: DateTime!
   deletedAt: DateTime
-  isOverridden: Boolean!
+  isOverridden: Boolean @deprecated(reason: "isOverridden is deprecated")
 }
 
 type PageLayout {
@@ -3471,6 +3471,7 @@ type Mutation {
   destroyPageLayout(id: String!): Boolean!
   updatePageLayoutWithTabsAndWidgets(id: String!, input: UpdatePageLayoutWithTabsInput!): PageLayout!
   resetPageLayoutWidgetToDefault(id: String!): PageLayoutWidget!
+  resetPageLayoutTabToDefault(id: String!): PageLayoutTab!
   createPageLayoutWidget(input: CreatePageLayoutWidgetInput!): PageLayoutWidget!
   updatePageLayoutWidget(id: String!, input: UpdatePageLayoutWidgetInput!): PageLayoutWidget!
   destroyPageLayoutWidget(id: String!): Boolean!