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/com_ptr.hpp

@@ -0,0 +1,69 @@
+/* Copyright (c) 2025-2026 Hans-Kristian Arntzen for Valve Corporation
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <utility>
+
+template <typename T>
+class ComPtr
+{
+public:
+	ComPtr() = default;
+	~ComPtr() { release(); }
+
+	ComPtr(const ComPtr &other) { *this = other; }
+	ComPtr &operator=(const ComPtr &other);
+	ComPtr &operator=(ComPtr &&other) noexcept;
+
+	ComPtr(ComPtr &&other) noexcept { *this = std::move(other); }
+	ComPtr &operator=(T *ptr_) { release(); ptr = ptr_; return *this; }
+
+	T *operator->() { return ptr; }
+	T *get() const { return ptr; }
+	void **ppv() { release(); return reinterpret_cast<void **>(&ptr); }
+
+	void operator&() = delete;
+	explicit operator bool() const { return ptr != nullptr; }
+
+	static ComPtr create() { return ComPtr(new T); }
+	static ComPtr addref(T *ptr_) { ptr_->AddRef(); return ComPtr(ptr_); }
+
+private:
+	T *ptr = nullptr;
+	void release()
+	{
+		if (ptr)
+			ptr->Release();
+		ptr = nullptr;
+	}
+	ComPtr *self_addr() { return this; }
+	const ComPtr *self_addr() const { return this; }
+	ComPtr(T *ptr_) : ptr(ptr_) {}
+};
+
+template <typename T>
+ComPtr<T> &ComPtr<T>::operator=(const ComPtr &other)
+{
+	if (this == other.self_addr())
+		return *this;
+	if (other.ptr)
+		other.ptr->AddRef();
+	release();
+	ptr = other.ptr;
+	return *this;
+}
+
+template <typename T>
+ComPtr<T> &ComPtr<T>::operator=(ComPtr &&other) noexcept
+{
+	if (this == other.self_addr())
+		return *this;
+	release();
+	if (other.ptr)
+		ptr = other.ptr;
+	other.ptr = nullptr;
+	return *this;
+}
+