graphics: respect Windows dark mode (#765)

Only affects the caption bar.

Should work for:

- [x] standalone configurator
- [x] dx9 games, including multi-window games like gitadora
- [x] Unity games

src/spice2x/hooks/graphics/backends/d3d11/d3d11_swapchain.cpp

@@ -27,6 +27,7 @@
 #include "hooks/graphics/graphics.h"
 #include "launcher/launcher.h"
 #include "misc/eamuse.h"
+#include "util/utils.h"
 
 // --------------------------------------------------------------------------
 // overlay render bridge
@@ -123,6 +124,10 @@ void try_create_overlay(IDXGISwapChain *swapchain) {
         return;
     }
 
+    // theme the native title bar; first present is the only reliable point for
+    // windows whose swapchain bypasses our factory hooks (e.g. UnityPlayer.dll)
+    set_window_dark_titlebar(desc.OutputWindow);
+
     ID3D11Device *device = nullptr;
     if (FAILED(swapchain->GetDevice(IID_PPV_ARGS(&device))) || !device) {
         return;