fix(model): add @JsonIgnore on PersonNameAlias.person to prevent LazyInitializationException

Jackson tried to serialize the lazy Person proxy when returning
alias list, causing a "no session" error. The back-reference is
only needed for JPA navigation, not for API responses.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/main/java/org/raddatz/familienarchiv/model/PersonNameAlias.java

@@ -1,5 +1,6 @@
 package org.raddatz.familienarchiv.model;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import io.swagger.v3.oas.annotations.media.Schema;
 import jakarta.persistence.*;
 import lombok.*;
@@ -23,6 +24,7 @@ public class PersonNameAlias {
 
     @ManyToOne(fetch = FetchType.LAZY)
     @JoinColumn(name = "person_id", nullable = false)
+    @JsonIgnore
     private Person person;
 
     @Column(name = "last_name", nullable = false)