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/pyrowave-shared.def

@@ -0,0 +1,38 @@
+LIBRARY libpyrowave-shared-0.dll
+
+EXPORTS
+	pyrowave_get_api_version
+	pyrowave_create_default_device
+	pyrowave_create_device_by_compat
+	pyrowave_create_device
+	pyrowave_device_set_command_buffer
+	pyrowave_device_report_performance_stats
+	pyrowave_device_get_vk_device_handles
+	pyrowave_device_confirm_interop_support
+	pyrowave_device_set_queue_type
+	pyrowave_device_destroy
+	pyrowave_sync_object_create
+	pyrowave_sync_object_get_semaphore
+	pyrowave_sync_object_export_handle
+	pyrowave_sync_object_cpu_wait
+	pyrowave_sync_object_cpu_signal
+	pyrowave_sync_object_destroy
+	pyrowave_image_create
+	pyrowave_image_get_handle
+	pyrowave_image_get_image_view
+	pyrowave_image_destroy
+	pyrowave_encoder_create
+	pyrowave_encoder_encode_gpu_synchronous
+	pyrowave_encoder_encode_cpu_synchronous
+	pyrowave_encoder_compute_num_packets
+	pyrowave_encoder_packetize
+	pyrowave_encoder_destroy
+	pyrowave_decoder_device_prefers_fragment_path
+	pyrowave_decoder_create
+	pyrowave_decoder_clear
+	pyrowave_decoder_push_packet
+	pyrowave_decoder_decode_is_ready
+	pyrowave_decoder_decode_gpu_buffer
+	pyrowave_decoder_decode_cpu_buffer_synchronous
+	pyrowave_decoder_destroy
+