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/buffer_pool.hpp

@@ -0,0 +1,91 @@
+/* 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 "vulkan_headers.hpp"
+#include "intrusive.hpp"
+#include <vector>
+#include <algorithm>
+
+namespace Vulkan
+{
+class Device;
+class Buffer;
+
+struct BufferBlockAllocation
+{
+	uint8_t *host;
+	Util::IntrusivePtr<Buffer> buffer;
+	VkDeviceSize offset;
+	VkDeviceSize padded_size;
+};
+
+class BufferBlock
+{
+public:
+	~BufferBlock();
+
+	BufferBlockAllocation allocate(VkDeviceSize allocate_size);
+	bool is_mapped() const { return mapped != nullptr; }
+	const Buffer &get_buffer() const { return *buffer; }
+	void unmap(Device &device);
+
+	VkDeviceSize get_offset() const { return offset; }
+	VkDeviceSize get_size() const { return size; }
+
+private:
+	friend class BufferPool;
+	Util::IntrusivePtr<Buffer> buffer;
+	VkDeviceSize offset = 0;
+	VkDeviceSize alignment = 0;
+	VkDeviceSize size = 0;
+	uint8_t *mapped = nullptr;
+};
+
+class BufferPool
+{
+public:
+	~BufferPool();
+	void init(Device *device, VkDeviceSize block_size, VkDeviceSize alignment, VkBufferUsageFlags usage);
+	void reset();
+
+	void set_max_retained_blocks(size_t max_blocks);
+
+	VkDeviceSize get_block_size() const
+	{
+		return block_size;
+	}
+
+	BufferBlock request_block(VkDeviceSize minimum_size);
+	void recycle_block(BufferBlock &block);
+
+private:
+	Device *device = nullptr;
+	VkDeviceSize block_size = 0;
+	VkDeviceSize alignment = 0;
+	VkBufferUsageFlags usage = 0;
+	size_t max_retained_blocks = 0;
+	std::vector<BufferBlock> blocks;
+	BufferBlock allocate_block(VkDeviceSize size);
+};
+}