Fix MSVC compiler warnings and platform-specific configuration

- Fix MSVC /W3 overriding warnings by using platform-specific flags
- Add explicit /W4 flag for Windows builds
- Fix size_t to int conversion warning in examples/basic_usage.cpp
- Add platform-specific compiler flag configuration to avoid conflicts
- Improve xmake.lua with better Windows/Linux compatibility

Author: WenyinWei

examples/basic_usage.cpp

@@ -318,7 +318,7 @@ void demonstrate_eda_design_rules() {
         for (size_t i = 0; i < eda_components.size(); ++i) {
             auto sharp_angles = eda_components[i].get_sharp_angles(process.sharp_angle_limit);
             if (!sharp_angles.empty()) {
-                violations += sharp_angles.size();
+                violations += static_cast<int>(sharp_angles.size());
                 std::cout << "  " << component_names[i] << ": " << sharp_angles.size() 
                          << " sharp angle violations" << std::endl;
             }

xmake.lua

@@ -7,7 +7,21 @@ set_languages("c++17")
 
 -- Configure compiler options
 add_rules("mode.debug", "mode.release")
-add_cxxflags("-Wall", "-Wextra", "-Wpedantic")
+
+-- Platform-specific compiler flags to avoid MSVC warnings
+if is_plat("windows") then
+    -- Use /W4 for MSVC instead of conflicting with default /W3
+    add_cxxflags("/W4")
+    if is_mode("release") then
+        add_cxxflags("/O2")
+    end
+else
+    -- GCC/Clang flags for Linux/macOS
+    add_cxxflags("-Wall", "-Wextra")
+    -- Only add pedantic for non-MSVC compilers
+    set_policy("check.auto_ignore_flags", false)
+    add_cxxflags("-Wpedantic", {force = true})
+end
 
 if is_mode("debug") then
     add_defines("DEBUG")