feat: Implement merge person functionality with associated request and repository methods

libertas_api/src/services/person_service.rs

@@ -183,4 +183,36 @@ impl PersonService for PersonServiceImpl {
             .remove_share(person_id, target_user_id)
             .await
     }
+
+    async fn merge_people(
+        &self,
+        target_person_id: Uuid,
+        source_person_id: Uuid,
+        user_id: Uuid,
+    ) -> CoreResult<()> {
+        if target_person_id == source_person_id {
+            return Err(CoreError::Validation(
+                "Cannot merge the same person".to_string(),
+            ));
+        }
+
+        self.auth_service
+            .check_permission(
+                Some(user_id),
+                authz::Permission::EditPerson(target_person_id),
+            )
+            .await?;
+        self.auth_service
+            .check_permission(
+                Some(user_id),
+                authz::Permission::EditPerson(source_person_id),
+            )
+            .await?;
+
+        self.face_repo
+            .reassign_person(source_person_id, target_person_id)
+            .await?;
+
+        self.person_repo.delete(source_person_id).await
+    }
 }