fix: Add cascading to Agent

src/main/java/cz/fi/muni/pa165/seminar4/group7/secretservice/entity/Agent.java

@@ -22,17 +22,17 @@ public class Agent {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
-    @OneToMany
+    @OneToMany(cascade = CascadeType.ALL)
     @Setter(AccessLevel.NONE)
     private List<Skill> skills = new ArrayList<>();
 
     private String training = "";
 
-    @OneToMany
+    @OneToMany(cascade = CascadeType.ALL)
     @Setter(AccessLevel.NONE)
     private List<CodeName> codeNames = new ArrayList<>();
 
-    @OneToMany(mappedBy = "agent")
+    @OneToMany(mappedBy = "agent", cascade = CascadeType.ALL)
     @Getter
     private List<AgentAssignment> agentAssignments = new ArrayList<>();