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

.vscode/c_cpp_properties.json

@@ -0,0 +1,15 @@
+{
+    "configurations": [
+        {
+            "name": "Linux",
+            "compileCommands": "${workspaceFolder}/build/compile_commands.json",
+            "cStandard": "c17",
+            "cppStandard": "c++17",
+            "intelliSenseMode": "linux-gcc-x64"
+        },
+        {
+            
+        }
+    ],
+    "version": 4
+}