feat(host): vendor PyroWave + minimal Granite subset as crates/pyrowave-sys

Phase 0 of design/pyrowave-codec-plan.md — the opt-in wired-LAN ultra-low-
latency codec. Vendored at upstream 509e4f88 (API 0.4.0, Granite 44362775,
volk + vulkan-headers pins in PUNKTFUNK-VENDOR.txt), pruned to the 6.6 MB
the standalone no-renderer build needs; scripts/vendor-pyrowave.sh
reproduces the tree (a pin bump is protocol-affecting, plan §4.2).

build.rs drives the wrapper CMakeLists (static archives incl. a static
C-API lib upstream only ships shared) + bindgen over pyrowave.h; Linux and
Windows only, empty stub elsewhere (Apple gets a native Metal port, §4.7).
Offline-safe by construction: no network, no system lib, vendored Vulkan
headers — same model as the opus dep (flatpak builder has no network).

Phase-0 validation on .21 (RTX 5070 Ti, driver 610.43.03):
- upstream pyrowave-c-test + interop test (incl. dmabuf/DRM-modifier
  Vulkan<->Vulkan) pass, from the pristine AND the pruned tree
- GPU kernel times at ~1.6 bpp noise: encode/decode 0.090/0.042 ms @800p,
  0.146/0.067 @1080p, 0.226/0.103 @1440p, 0.477/0.201 @4K — order of
  magnitude under NVENC's 1-2 ms retrieve, CBR lands within ~100 B of
  target
- cargo test -p pyrowave-sys green (static link + API-version pin check)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/pyrowave-sys/vendor/pyrowave/Granite/vulkan/wsi_dxgi.hpp

@@ -0,0 +1,84 @@
+/* Copyright (c) 2017-2026 Hans-Kristian Arntzen
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+
+#include "device.hpp"
+#include "image.hpp"
+#include "d3d12.h"
+#include "dxgi1_6.h"
+#include "small_vector.hpp"
+#include "dynamic_library.hpp"
+#include <wrl.h>
+
+namespace Vulkan
+{
+template <typename T>
+using ComPtr = Microsoft::WRL::ComPtr<T>;
+
+class DXGIInteropSwapchain
+{
+public:
+	bool init_interop_device(Device &device);
+	~DXGIInteropSwapchain();
+
+	bool init_swapchain(HWND hwnd, VkSurfaceFormatKHR format, unsigned width, unsigned height, unsigned count);
+	VkImage get_vulkan_image() const;
+	VkSurfaceFormatKHR get_current_surface_format() const;
+
+	bool acquire(Semaphore &acquire_semaphore);
+	bool present(Semaphore release_semaphore, bool vsync);
+	bool wait_latency(unsigned latency_frames);
+
+private:
+	Device *vk_device = nullptr;
+	Util::DynamicLibrary d3d12_lib, dxgi_lib;
+	HWND hwnd = nullptr;
+	HANDLE latency_handle = nullptr;
+	ComPtr<ID3D12Device4> device;
+	ComPtr<ID3D12CommandQueue> queue;
+	ComPtr<IDXGIFactory5> dxgi_factory;
+	ComPtr<IDXGISwapChain3> swapchain;
+	ComPtr<ID3D12GraphicsCommandList> list;
+	ComPtr<ID3D12Fence> fence;
+	Semaphore vk_fence;
+	uint64_t fence_value = 0;
+	VkSurfaceFormatKHR surface_format = {};
+	bool allow_tearing = false;
+
+	struct PerFrameState
+	{
+		ComPtr<ID3D12CommandAllocator> allocator;
+		ComPtr<ID3D12Resource> backbuffer;
+		uint64_t wait_fence_value = 0;
+	};
+	Util::SmallVector<PerFrameState> backbuffers;
+	ComPtr<ID3D12Resource> blit_backbuffer;
+	ImageHandle vulkan_backbuffer;
+
+	bool setup_per_frame_state(PerFrameState &state, unsigned index);
+	void reset_backbuffer_state();
+
+	uint64_t completed_presents = 0;
+	uint64_t completed_waits = 0;
+};
+}