feat: 添加随机内容模块并优化安全配置

新增Nonsense相关实体、DTO、Repository、Service和Controller，实现随机内容的CRUD功能
优化CORS和安全配置，增加更精细的权限控制和错误处理
移除Article和Message中不必要的验证注解，调整部分API的权限要求

src/main/java/com/qf/myafterprojecy/pojo/dto/MessageDto.java

@@ -20,6 +20,8 @@ public class MessageDto {
     private Integer articleid;
     
     private Integer likes;
+    
+    private String messageimg;
 
     public Integer getReplyid() {
         return replyid;
@@ -92,4 +94,12 @@ public class MessageDto {
     public void setLikes(Integer likes) {
         this.likes = likes;
     }
+
+    public String getMessageimg() {
+        return messageimg;
+    }
+
+    public void setMessageimg(String messageimg) {
+        this.messageimg = messageimg;
+    }
 }

src/main/java/com/qf/myafterprojecy/pojo/dto/NonsenseDto.java

@@ -0,0 +1,36 @@
+package com.qf.myafterprojecy.pojo.dto;
+
+import java.util.Date;
+
+public class NonsenseDto {
+    private Integer id;
+
+    private String content;
+    
+    private Date time;
+
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    public Date getTime() {
+        return time;
+    }
+
+    public void setTime(Date time) {
+        this.time = time;
+    }
+}