## Sync page layouts, tabs, and widgets
Adds the ability for SDK applications to synchronize `pageLayout`,
`pageLayoutTab`, and `pageLayoutWidget` entities, following the same
pattern established in #18003 for views and navigation menu items.
### Changes
**`twenty-shared`**
- New `PageLayoutManifest`, `PageLayoutTabManifest`, and
`PageLayoutWidgetManifest` types with a hierarchical structure (page
layout → tabs → widgets)
- Added `pageLayouts: PageLayoutManifest[]` to the `Manifest` type
**`twenty-sdk`**
- New `definePageLayout()` SDK function with validation for
universalIdentifier, name, and nested tabs/widgets
- Wired into the manifest extraction and build pipeline
(`DefinePageLayout` target function, `PageLayouts` entity key)
- Exported from the SDK entry point
**`twenty-server`**
- Added `pageLayout`, `pageLayoutTab`, `pageLayoutWidget` to
`APPLICATION_MANIFEST_METADATA_NAMES`
- New conversion utilities: manifest → universal flat entity for all
three entity types
- Updated `computeApplicationManifestAllUniversalFlatEntity
