fix: 修复 Types.h 缺少头文件保护导致的重复定义错误

- Types.h: 添加 #pragma once 防止重复包含
- CMakeLists.txt: C++ 标准 17 → 20
- App/CMakeLists.txt: 移除重复的 C++11 覆盖，统一继承根 CMake 标准
- Axis.cpp: 添加 #include <string> 显式包含

CMakeLists.txt

@@ -34,9 +34,9 @@ elseif(UNIX) # 注意：Linux和macOS都满足UNIX为TRUE，所以通常先判
 endif()
 
 
-set(CMAKE_C_STANDARD 17)
+set(CMAKE_C_STANDARD 20)
 set(CMAKE_C_STANDARD_REQUIRED ON)
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 add_subdirectory(${CMAKE_SOURCE_DIR}/MotionLib)