Fix Windows DLL load by using static MSVC runtime

- Add MSVC_RUNTIME_LIBRARY=MultiThreaded to statically link MSVC runtime
- Build CFD library with same static runtime to avoid runtime mismatch
- This eliminates dependency on VC++ redistributable

Author: shaia

.github/workflows/build-wheels.yml

@@ -49,7 +49,7 @@ jobs:
       - name: Build CFD library (Windows)
         if: runner.os == 'Windows'
         run: |
-          cmake -S cfd -B cfd/build -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF
+          cmake -S cfd -B cfd/build -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded
           cmake --build cfd/build --config Release
           echo "=== CFD library built ==="
           dir cfd\build\lib\Release

CMakeLists.txt

@@ -59,6 +59,12 @@ set_target_properties(cfd_python PROPERTIES
     C_STANDARD 11
 )
 
+# On Windows, use static MSVC runtime to avoid requiring VC++ redistributable
+if(MSVC)
+    set_property(TARGET cfd_python PROPERTY
+        MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
+endif()
+
 # Configure stable ABI if enabled
 if(CFD_USE_STABLE_ABI)
     # Define Py_LIMITED_API for Python 3.8+ stable ABI