Fix #141158: Fullscreen startup file causes white flicker with Vulkan backend

When launching Blender via blender-launcher.exe, the window briefly
displays incorrectly on startup when using the Vulkan backend. This is
caused by not properly handling the GHOST_kWindowStateFullScreen case.

Previously, even if the window state was set to fullscreen, nCmdShow
would default to SW_SHOWNORMAL or SW_SHOWNOACTIVATE. With this fix,
nCmdShow is explicitly set to SW_SHOWMAXIMIZED when the window is in
fullscreen state, preventing the flicker.

Pull Request: https://projects.blender.org/blender/blender/pulls/141518

intern/ghost/intern/GHOST_WindowWin32.cc

@@ -192,6 +192,7 @@ GHOST_WindowWin32::GHOST_WindowWin32(GHOST_SystemWin32 *system,
   /* Show the window. */
   int nCmdShow;
   switch (state) {
+    case GHOST_kWindowStateFullScreen:
     case GHOST_kWindowStateMaximized:
       nCmdShow = SW_SHOWMAXIMIZED;
       break;