cli: add --gpu <index> to select a Vulkan physical deviceFeature gpu select (#417)

* cli: add --gpu <index> to select a Vulkan physical device

Select the Vulkan physical device by enumeration index, defaulting to
automatic selection (-1). Invalid or out-of-range indices fall back to
automatic selection with a clear message, and the selected device is
logged.

Co-Authored-By: Claude <noreply@anthropic.com>

* cli: reject invalid --gpu index, translate comments, apply clang-format

An invalid --gpu index now prints an error and exits with code 1 (usage),
matching --user-id / --present-mode / --console-language. The automatic
fallback is kept only for out-of-range indices detected at runtime.
Comments translated to English and the touched files brought in line
with clang-format (pre-commit v22.1.3).

Co-Authored-By: Claude <noreply@anthropic.com>

* cli: simplify Vulkan device selection

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: nmzik <Nmzik@mail.ru>

src/common/emulatorConfig.cpp

@@ -47,6 +47,10 @@ PresentMode GetPresentMode() {
 	return g_config->present_mode;
 }
 
+int32_t GetGpuIndex() {
+	return g_config->gpu_index;
+}
+
 bool FullscreenEnabled() {
 	return g_config->fullscreen_enabled;
 }