refactor: 优化响应状态码映射，权限不足时返回403 Forbidden

src/main/java/com/youlai/boot/common/result/ResponseWriter.java

@@ -103,6 +103,9 @@ public final class ResponseWriter {
 
     /**
      * 根据业务结果码映射HTTP状态码
+     * 401: 未认证（token无效/过期）
+     * 403: 权限不足
+     * 400: 其他业务错误
      *
      * @param resultCode 业务结果码
      * @return HTTP状态码
@@ -112,6 +115,7 @@ public final class ResponseWriter {
             case ACCESS_UNAUTHORIZED,
                  ACCESS_TOKEN_INVALID,
                  REFRESH_TOKEN_INVALID -> HttpStatus.UNAUTHORIZED.value();
+            case ACCESS_PERMISSION_EXCEPTION -> HttpStatus.FORBIDDEN.value();
             default -> HttpStatus.BAD_REQUEST.value();
         };
     }

src/main/java/com/youlai/boot/framework/security/handler/MyAccessDeniedHandler.java

@@ -18,7 +18,8 @@ public class MyAccessDeniedHandler implements AccessDeniedHandler {
 
     @Override
     public void handle(HttpServletRequest request, HttpServletResponse response, AccessDeniedException accessDeniedException) {
-        ResponseWriter.writeError(response, ResultCode.ACCESS_UNAUTHORIZED);
+        // 权限不足返回 403 Forbidden
+        ResponseWriter.writeError(response, ResultCode.ACCESS_PERMISSION_EXCEPTION);
     }
 
 }