Create twenty app improvements (#20688)

create-twenty-app updates:
- remove --example option
- sync --once when scaffolding an applicaiton
- rename --api-url option to --workspace-url
- create a standalone page when scaffolding an app
<img width="1494" height="765" alt="image"
src="https://github.com/user-attachments/assets/0e35ed0c-b0aa-466c-9f56-7939294fd2cf"
/>

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packages/twenty-server/src/engine/metadata-modules/page-layout/dtos/page-layout.dto.ts

@@ -32,6 +32,9 @@ export class PageLayoutDTO {
   @Field(() => UUIDScalarType, { nullable: true })
   defaultTabToFocusOnMobileAndSidePanelId?: SerializedRelation;
 
+  @Field(() => UUIDScalarType, { nullable: false })
+  universalIdentifier: string;
+
   @Field()
   createdAt: Date;