chore: Verify item.id is correctly passed to the frontend

[zigzagdev]

Parent issue

#475

Overview

Confirm that item.id (matching the primary key of world_heritage_site_images) is included in the API response and surfaces in the WorldHeritageVm view model consumed by HeritageCard.

Checklist

• API response for the heritage list includes the id field from world_heritage_site_images
• WorldHeritageVm type definition exposes id: number
• HeritageCard receives a non-null item.id at runtime (verify via console.log or React DevTools)

Acceptance criteria

item.id in HeritageCard matches the corresponding row's id in world_heritage_site_images