Implement UUID generation in addPersonToList and ensure uniqueness across existing nodes

include/users.h

@@ -26,6 +26,16 @@ typedef struct node
     struct node *next;
 } node_t;
 
+/**
+ * @brief Generates a unique identifier (UUID) for a new node in the linked list.
+ *
+ * This function traverses the linked list starting from the given head node
+ * and generates a unique 16-bit unsigned integer identifier that does not
+ * conflict with any existing UUIDs in the list.
+ *
+ * @param _head Pointer to the head node of the linked list.
+ * @return A 16-bit unsigned integer representing the generated UUID.
+ */
 uint16_t generateUUID(node_t *_head);
 
 uint16_t searchUUIDByName(node_t *_head);