cfg: d3d9 standalone configurator (#720)

## Description of change
**Configurator (spicecfg.exe)**

- Attempts to create a D3D9 device on startup and uses the hardware
ImGui DX9 path when successful; falls back to the existing software
rasterizer automatically if D3D9 init fails.
- Rewrites the configurator window loop: refresh-rate-aware render
timer, minimize/resize/`WM_DISPLAYCHANGE` handling, direct Win32 ->
ImGui input (keyboard, mouse, wheel), and optimized software painting
via `SetDIBitsToDevice` instead of per-frame GDI `HBITMAP` allocation.

**Overlay / input (scoped to standalone configurator)**

- Skips expensive per-frame rawinput polling in
`ImGui_ImplSpice_NewFrame` when `CONFIGURATOR_STANDALONE` is set (Win32
messages drive input instead).
- Adds software-renderer idle-frame detection (`sw_pixels_dirty` +
draw-data hash) so spicecfg only repaints when pixels actually change.
- Adds `ImGuiWindowFlags_NoScrollWithMouse` on the configurator root
window to prevent scroll jolt on non-scrollable child widgets.

src/spice2x/cfg/configurator.cpp

@@ -1,6 +1,9 @@
-#include "configurator.h"
+#include "configurator.h"
+
+#include <d3d9.h>
 
 #include "overlay/overlay.h"
+#include "util/logging.h"
 
 namespace cfg {
 
@@ -16,11 +19,74 @@ namespace cfg {
         CONFIGURATOR_STANDALONE = false;
     }
 
+    // Attempt to bring up a D3D9 device backing the configurator's window so the
+    // overlay can use the hardware-accelerated imgui_impl_dx9 path instead of
+    // the CPU rasterizer. Returns true if both Direct3DCreate9 and CreateDevice
+    // succeed; the caller falls back to overlay::create_software() otherwise so
+    // that environments without D3D9 (Wine without dxvk, headless test boxes,
+    // GPUs whose drivers reject HAL) still get a working configurator.
+    static bool try_init_d3d9(ConfiguratorWindow &wnd) {
+        if (wnd.hWnd == nullptr) {
+            return false;
+        }
+
+        IDirect3D9 *d3d = Direct3DCreate9(D3D_SDK_VERSION);
+        if (d3d == nullptr) {
+            log_warning("configurator", "Direct3DCreate9 returned NULL, falling back to software renderer");
+            return false;
+        }
+
+        D3DPRESENT_PARAMETERS pp {};
+        pp.Windowed = TRUE;
+        pp.SwapEffect = D3DSWAPEFFECT_DISCARD;
+        // D3DFMT_UNKNOWN -> driver picks the current desktop format
+        pp.BackBufferFormat = D3DFMT_UNKNOWN;
+        pp.BackBufferWidth = static_cast<UINT>(wnd.client_width);
+        pp.BackBufferHeight = static_cast<UINT>(wnd.client_height);
+        pp.hDeviceWindow = wnd.hWnd;
+        pp.EnableAutoDepthStencil = FALSE;
+        pp.PresentationInterval = D3DPRESENT_INTERVAL_ONE;
+
+        IDirect3DDevice9 *device = nullptr;
+        // SOFTWARE_VERTEXPROCESSING is the most compatible behavior flag; the UI
+        // is tiny so we don't need hardware T&L. FPU_PRESERVE keeps our floating
+        // point environment intact in case other spice code relies on it.
+        const DWORD behavior_flags = D3DCREATE_SOFTWARE_VERTEXPROCESSING | D3DCREATE_FPU_PRESERVE;
+        HRESULT hr = d3d->CreateDevice(
+                D3DADAPTER_DEFAULT,
+                D3DDEVTYPE_HAL,
+                wnd.hWnd,
+                behavior_flags,
+                &pp,
+                &device);
+        if (FAILED(hr) || device == nullptr) {
+            log_warning("configurator",
+                "D3D9 CreateDevice failed (hr={:#x}), falling back to software renderer",
+                static_cast<unsigned int>(hr));
+            d3d->Release();
+            return false;
+        }
+
+        wnd.d3d = d3d;
+        wnd.device = device;
+        wnd.pp = pp;
+        wnd.use_d3d9 = true;
+        return true;
+    }
+
     void Configurator::run() {
 
-        // create instance
+        // bring up the overlay against either a real D3D9 device or the software
+        // rasterizer. The choice is one-shot - the in-game overlay always uses
+        // the same renderer the configurator picked here.
         overlay::ENABLED = true;
-        overlay::create_software(this->wnd.hWnd);
+        if (try_init_d3d9(this->wnd)) {
+            log_info("configurator", "using D3D9 hardware-accelerated renderer");
+            overlay::create_d3d9(this->wnd.hWnd, this->wnd.d3d, this->wnd.device);
+        } else {
+            log_info("configurator", "using software renderer");
+            overlay::create_software(this->wnd.hWnd);
+        }
         overlay::OVERLAY->set_active(true);
         overlay::OVERLAY->hotkeys_enable = false;
         ImGui::GetIO().MouseDrawCursor = false;