macOS (Apple Silicon) support: native build running under Rosetta 2 with MoltenVK (#102)

* macos: POSIX platform layer (host fault handler, virtual memory)

- hostException: Mach/POSIX signal-based host fault handler mirroring the
  Windows vectored handler (SIGSEGV/SIGBUS/SIGILL), behind
  '#elif defined(__APPLE__)'. Windows and Linux branches are untouched.
- sysLinuxVirtual: mach_vm_region-based is_mapped (no /proc/self/maps on
  macOS), PTHREAD_MUTEX_NORMAL, and a MAP_FIXED carve-in-place allocator that
  never leaves an unmapped hole for dyld/Rosetta/Metal to claim. All
  __APPLE__-guarded; the original Linux allocator path is preserved verbatim.
- sysLinuxDbg/sysLinuxFileIO: libgen.h for basename(), and a POSIX
  opendir/readdir implementation of SysFileGetDents (previously a stub).

* macos: guest kernel backing, threads, and POSIX libs

- memory/memoryAddressSpace: anonymous shm_open backing (macOS has no
  memfd_create) and re-reserve-on-unmap so a guest MAP_FIXED remap never
  destroys a host mapping (__APPLE__-guarded). Drops host <sys/mman.h> MAP_*
  macros so the guest's constexpr MAP_* constants compile (no-op on Windows).
- pthread: undef the host PTHREAD_STACK_MIN macro; on non-Windows, pin the
  stack-switch asm's guest rsp/rbp to callee-saved r14/r15 (the template
  clobbers r12/r13); __APPLE__ no-op for the absent pthread_condattr_setclock.
  The Windows stack-switch asm is byte-identical.
- network: define SOCKET/INVALID_SOCKET for the non-Windows paths (were
  undefined at 20+ use sites), and rename the non-Windows kernel_clock_*
  helpers to the CamelCase names the callers already use. Both repair the
  shared non-Windows build. Integer reinterpret_cast -> static_cast.

* loader: pin stack-switch asm operands to callee-saved registers

RunEntry switches to the guest stack with an asm template that clobbers
r12/r13 before consuming its inputs. With plain "r" constraints the compiler
may place func/guest_rsp/guest_rbp into r12/r13, so 'callq *func' jumps
through the saved host rsp -- a latent miscompile on every platform that any
unrelated codegen change can trigger. Pin the inputs to rbx/r14/r15, which the
template never touches and the SysV callee preserves.

General correctness fix (not macOS-specific); the same fix is applied to
pthread RunOnGuestStack.

* macos: Vulkan/MoltenVK graphics enablement

- pageManager: GPU write-tracking via Mach VM queries + mprotect (mprotect
  cannot report the previous protection, so the expected-old check is dropped),
  thread id via pthread_mach_thread_np, 4 KB page-size check -- __APPLE__-guarded.
- shaders/renderDraw/vulkanWindow: MoltenVK lacks VK_EXT_color_write_enable,
  VK_EXT_depth_clip_enable and depthBounds; fall back to static color-write
  masks and default depth clipping, request VK_KHR_portability_subset, and
  reuse the graphics queue for present when only one queue is exposed. Non-Apple
  pipeline/extension setup is unchanged.
- window: optional borderless window (KYTY_BORDERLESS) to sidestep a Rosetta
  NSException in macOS window chrome.

* graphics: macOS thread identity for region tracking

Region-ownership locks resolve the current thread via GetCurrentThreadId()
on Windows and EXIT elsewhere. Use the Mach thread port on macOS (nonzero
per-thread id; 0 stays the no-owner sentinel).

* macos: marshal AppKit window operations to the main thread

The present worker thread shows the window, updates its icon and title, and
recreates a lost Vulkan surface. AppKit traps with 'Must only be used from the
main thread' when these run off the main thread. Route them through a small
task queue drained by the SDL main loop (an SDL_USEREVENT wakes the loop when
it is blocked in SDL_WaitEvent). Title updates are fire-and-forget; showing
the window and surface recreation wait for completion.

Windows and Linux call the SDL functions directly, as before.

* build: ignore the _Build output directory

_Build is the conventional out-of-tree build location (only _Build/vscode-clang
was ignored); a stray git add could sweep build artifacts into a commit.

* macos: isolate stack-switch workaround

---------

Co-authored-by: nmzik <Nmzik@mail.ru>

src/graphics/presentation/window/vulkanWindow.cpp

@@ -217,7 +217,9 @@ static void VulkanFindPhysicalDevice(vk::Instance instance, vk::SurfaceKHR surfa
 
 		if (color_write_ext.colorWriteEnable != VK_TRUE) {
 			LOGF("colorWriteEnable is not supported\n");
+#if !defined(__APPLE__)
 			skip_device = true;
+#endif
 		}
 
 		if (depth_clip_control.depthClipControl != VK_TRUE) {
@@ -226,7 +228,9 @@ static void VulkanFindPhysicalDevice(vk::Instance instance, vk::SurfaceKHR surfa
 		}
 		if (depth_clip_enable.depthClipEnable != VK_TRUE) {
 			LOGF("depthClipEnable is not supported\n");
+#if !defined(__APPLE__)
 			skip_device = true;
+#endif
 		}
 
 		if (features12.samplerMirrorClampToEdge != VK_TRUE) {
@@ -271,7 +275,9 @@ static void VulkanFindPhysicalDevice(vk::Instance instance, vk::SurfaceKHR surfa
 		}
 		if (device_features2.features.depthBounds != VK_TRUE) {
 			LOGF("depthBounds is not supported\n");
+#if !defined(__APPLE__)
 			skip_device = true;
+#endif
 		}
 		if (device_features2.features.shaderStorageImageWriteWithoutFormat != VK_TRUE) {
 			LOGF("shaderStorageImageWriteWithoutFormat is not supported\n");
@@ -494,7 +500,14 @@ static vk::Device VulkanCreateDevice(vk::PhysicalDevice physical_device, const V
 
 	vk::PhysicalDeviceDepthClipControlFeaturesEXT depth_clip_control {};
 	depth_clip_control.sType = vk::StructureType::ePhysicalDeviceDepthClipControlFeaturesEXT;
+	// MoltenVK lacks VK_EXT_depth_clip_enable and VK_EXT_color_write_enable, so drop those
+	// feature structs from the chain on macOS (the renderer falls back to default depth
+	// clipping and static color-write masks).
+#if defined(__APPLE__)
+	depth_clip_control.pNext = nullptr;
+#else
 	depth_clip_control.pNext = &depth_clip_enable;
+#endif
 	depth_clip_control.depthClipControl = VK_TRUE;
 
 	vk::PhysicalDeviceVulkan12Features features12 {};
@@ -541,7 +554,9 @@ static vk::Device VulkanCreateDevice(vk::PhysicalDevice physical_device, const V
 	device_features.fragmentStoresAndAtomics             = VK_TRUE;
 	device_features.samplerAnisotropy                    = VK_TRUE;
 	device_features.robustBufferAccess                   = VK_TRUE;
-	device_features.depthBounds                          = VK_TRUE;
+#if !defined(__APPLE__)
+	device_features.depthBounds                          = VK_TRUE; // unsupported by MoltenVK
+#endif
 	device_features.shaderStorageImageWriteWithoutFormat = VK_TRUE;
 	device_features.shaderStorageImageReadWithoutFormat  = VK_TRUE;
 	device_features.shaderImageGatherExtended            = VK_TRUE;
@@ -894,10 +909,20 @@ void WindowContext::CreateVulkan() {
 	}
 	surface = native_surface;
 
-	std::vector<const char*> device_extensions = {
-	    VK_KHR_SWAPCHAIN_EXTENSION_NAME, VK_EXT_DEPTH_CLIP_ENABLE_EXTENSION_NAME,
-	    VK_EXT_DEPTH_CLIP_CONTROL_EXTENSION_NAME, VK_EXT_COLOR_WRITE_ENABLE_EXTENSION_NAME,
-	    VK_KHR_PUSH_DESCRIPTOR_EXTENSION_NAME, "VK_KHR_maintenance1"};
+	std::vector<const char*> device_extensions = {VK_KHR_SWAPCHAIN_EXTENSION_NAME,
+	                                              VK_EXT_DEPTH_CLIP_CONTROL_EXTENSION_NAME,
+	                                              VK_KHR_PUSH_DESCRIPTOR_EXTENSION_NAME,
+	                                              "VK_KHR_maintenance1"};
+
+#if defined(__APPLE__)
+	// MoltenVK lacks VK_EXT_depth_clip_enable and VK_EXT_color_write_enable; the renderer
+	// falls back to default depth clipping and static color-write masks on macOS. It also
+	// requires VK_KHR_portability_subset per the Vulkan portability spec.
+	device_extensions.push_back("VK_KHR_portability_subset");
+#else
+	device_extensions.push_back(VK_EXT_DEPTH_CLIP_ENABLE_EXTENSION_NAME);
+	device_extensions.push_back(VK_EXT_COLOR_WRITE_ENABLE_EXTENSION_NAME);
+#endif
 
 #ifdef KYTY_ENABLE_DEBUG_PRINTF
 	if (Config::SpirvDebugPrintfEnabled()) {