Refactor ChatLogDao to use Timestamp and update ChatMessageMapper with proper JSON serialization using Jackson.

database/src/main/java/com/alttd/altitudeweb/database/chat/ChatLogDao.java

@@ -3,12 +3,14 @@ package com.alttd.altitudeweb.database.chat;
 import lombok.Builder;
 import lombok.Getter;
 
+import java.sql.Timestamp;
+
 @Builder
 @Getter
 public class ChatLogDao {
 
     private final String uuid;
-    private final long timeStamp;
+    private final Timestamp timeStamp;
     private final String server;
     private final String miniMessage;
     private final boolean blocked;