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/util/timer.cpp

@@ -0,0 +1,162 @@
+/* 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.
+ */
+
+#include "timer.hpp"
+#include "logging.hpp"
+
+#ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#else
+#include <time.h>
+#include <errno.h>
+#endif
+
+#ifdef __SSE2__
+#include <emmintrin.h>
+#endif
+
+namespace Util
+{
+FrameTimer::FrameTimer()
+{
+	reset();
+}
+
+void FrameTimer::reset()
+{
+	start = get_time();
+	last = start;
+	last_period = 0;
+}
+
+void FrameTimer::enter_idle()
+{
+	idle_start = get_time();
+}
+
+void FrameTimer::leave_idle()
+{
+	auto idle_end = get_time();
+	idle_time += idle_end - idle_start;
+}
+
+double FrameTimer::get_frame_time() const
+{
+	return double(last_period) * 1e-9;
+}
+
+double FrameTimer::frame()
+{
+	auto new_time = get_time() - idle_time;
+	last_period = new_time - last;
+	last = new_time;
+	return double(last_period) * 1e-9;
+}
+
+double FrameTimer::frame(double frame_time)
+{
+	last_period = int64_t(frame_time * 1e9);
+	last += last_period;
+	return frame_time;
+}
+
+double FrameTimer::get_elapsed() const
+{
+	return double(last - start) * 1e-9;
+}
+
+int64_t FrameTimer::get_time()
+{
+	return get_current_time_nsecs();
+}
+
+#ifdef _WIN32
+struct QPCFreq
+{
+	QPCFreq()
+	{
+		LARGE_INTEGER freq;
+		QueryPerformanceFrequency(&freq);
+		inv_freq = 1e9 / double(freq.QuadPart);
+	}
+
+	double inv_freq;
+} static static_qpc_freq;
+#endif
+
+int64_t get_current_time_nsecs()
+{
+#ifdef _WIN32
+	LARGE_INTEGER li;
+	if (!QueryPerformanceCounter(&li))
+		return 0;
+	return int64_t(double(li.QuadPart) * static_qpc_freq.inv_freq);
+#else
+	struct timespec ts = {};
+	constexpr auto timebase = CLOCK_MONOTONIC;
+	if (clock_gettime(timebase, &ts) < 0)
+		return 0;
+	return ts.tv_sec * 1000000000ll + ts.tv_nsec;
+#endif
+}
+
+void sleep_until_nsecs(int64_t timepoint)
+{
+#ifdef _WIN32
+	// Somewhat naive path. Improve this later.
+	int64_t d = get_current_time_nsecs() - timepoint;
+	if (d <= 0)
+		return;
+
+	// Assumes timer resolution has been set.
+	Sleep(d / 1000000);
+
+	// Spin the rest of the way.
+	while (get_current_time_nsecs() < timepoint)
+	{
+#ifdef __SSE2__
+		_mm_pause();
+#endif
+	}
+#else
+	constexpr auto timebase = CLOCK_MONOTONIC;
+	struct timespec ts = {};
+	ts.tv_sec = timepoint / 1000000000ll;
+	ts.tv_nsec = timepoint % 1000000000ll;
+	// Linux does not support clock_nanosleep with MONOTONIC_RAW :(
+	int ret;
+	while ((ret = clock_nanosleep(timebase, TIMER_ABSTIME, &ts, nullptr)) == EINTR) {}
+#endif
+}
+
+void Timer::start()
+{
+	t = get_current_time_nsecs();
+}
+
+double Timer::end()
+{
+	auto nt = get_current_time_nsecs();
+	return double(nt - t) * 1e-9;
+}
+}