ci: bundle MSVC runtime DLLs into the Windows artifact

The vcpkg-built openmpt.dll and its audio deps link the dynamic MSVC
runtime, so they require msvcp140/vcruntime140/vcruntime140_1 at runtime
even though rtrax.exe itself is static-CRT. Copy those three
redistributable DLLs from System32 into the bundle so the target machine
needs no Visual C++ redistributable installed.

Author: swilcox

.github/workflows/ci.yml

@@ -107,6 +107,12 @@ jobs:
           # libopenmpt.dll plus its runtime dependencies (ogg/vorbis/mpg123/
           # zlib/...) so the exe actually runs, not just links.
           Copy-Item "$env:VCPKG_INSTALLATION_ROOT/installed/x64-windows/bin/*.dll" $stage/
+          # The vcpkg DLLs link the *dynamic* MSVC runtime (rtrax.exe itself is
+          # static-CRT). Bundle the redistributable runtime DLLs so the target
+          # machine needs no Visual C++ redistributable installed at all.
+          foreach ($dll in 'msvcp140.dll', 'vcruntime140.dll', 'vcruntime140_1.dll') {
+            Copy-Item "$env:SystemRoot/System32/$dll" $stage/
+          }
           Copy-Item README.md, LICENSE $stage/
 
       - name: Upload Windows bundle