fix: 后端代码格式化

backend/src/main/java/com/openisle/exception/FieldException.java

@@ -9,11 +9,11 @@ import lombok.Getter;
  */
 @Getter
 public class FieldException extends RuntimeException {
-    private final String field;
 
-    public FieldException(String field, String message) {
-        super(message);
-        this.field = field;
-    }
+  private final String field;
+
+  public FieldException(String field, String message) {
+    super(message);
+    this.field = field;
+  }
 }
-

backend/src/main/java/com/openisle/exception/NotFoundException.java

@@ -4,7 +4,8 @@ package com.openisle.exception;
  * Exception representing a missing resource such as a post or user.
  */
 public class NotFoundException extends RuntimeException {
-    public NotFoundException(String message) {
-        super(message);
-    }
+
+  public NotFoundException(String message) {
+    super(message);
+  }
 }

backend/src/main/java/com/openisle/exception/RateLimitException.java

@@ -4,7 +4,8 @@ package com.openisle.exception;
  * Exception thrown when a user exceeds allowed action rate.
  */
 public class RateLimitException extends RuntimeException {
-    public RateLimitException(String message) {
-        super(message);
-    }
+
+  public RateLimitException(String message) {
+    super(message);
+  }
 }