refactor: 优化站内信及消息管理

1.新增站内信未读消息轮询
2.优化消息管理 API，移除部分无用 API
3.优化部分代码格式

continew-admin-common/src/main/java/top/charles7c/cnadmin/common/constant/SysConsts.java

@@ -67,9 +67,4 @@ public class SysConsts {
      * VO 描述类字段后缀
      */
     public static final String VO_DESCRIPTION_FIELD_SUFFIX = "String";
-
-    /**
-     * 系统消息类型
-     */
-    public static final String SYSTEM_MESSAGE_TYPE = "1";
 }

continew-admin-common/src/main/java/top/charles7c/cnadmin/common/enums/MessageTypeEnum.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2022-present Charles7c Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package top.charles7c.cnadmin.common.enums;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+import top.charles7c.cnadmin.common.base.IBaseEnum;
+import top.charles7c.cnadmin.common.constant.UIConsts;
+
+/**
+ * 消息类型枚举
+ *
+ * @author Charles7c
+ * @since 2023/11/2 20:08
+ */
+@Getter
+@RequiredArgsConstructor
+public enum MessageTypeEnum implements IBaseEnum<Integer> {
+
+    /** 系统消息 */
+    SYSTEM(1, "系统消息", UIConsts.COLOR_PRIMARY),;
+
+    private final Integer value;
+    private final String description;
+    private final String color;
+}