feat(video): Vulkan Video decode on the presenter's device (NVIDIA hw decode)

FFmpeg's Vulkan Video decoder now runs on the PRESENTER's own VkDevice —
the decoded VkImage feeds the existing CICP CSC pass directly: zero
copy, no interop, and NVIDIA gets hardware decode for the first time
(its VAAPI is unusable by design). One decode architecture for every
vendor going forward; VAAPI-dmabuf and software remain the fallbacks
(auto: vulkan → vaapi → software; PUNKTFUNK_DECODER=vulkan pins it).

Presenter: instance 1.3; probes VK_KHR_video_queue/decode_queue + codec
extensions, a VIDEO_DECODE queue family (+ its codec caps via
QueueFamilyVideoPropertiesKHR), and the samplerYcbcrConversion/
timelineSemaphore/synchronization2 features — all enabled at device
creation when present, exported as a VulkanDecodeDevice handle bundle.

Decoder: AVVulkanDeviceContext built over those handles via pf-ffvk
(features chain, extension lists, deprecated queue indices + the qf[]
map); get_format supplies OUR frames context with MUTABLE_FORMAT so the
presenter's per-plane views are legal; output is DecodedImage::VkFrame
carrying AVVkFrame/frames-ctx pointers plus the lock fns.

Present: R8+R8G8 plane views over the multiplanar image, the live sync
state read under the AVVulkanFramesContext lock, a timeline-semaphore
wait(sem_value)/signal(sem_value+1) folded into the submit, layout/
queue-family/sem_value written back per FFmpeg's contract, and the frame
guard parked in the retire queue until the fence. CSC pass + video
framebuffer are now unconditional (NVIDIA has no dmabuf-import path).

Verified on the RTX 5070 Ti: device creates with decode_qf=3,
caps=DECODE_H264|H265|AV1|VP9; swapchain unaffected. Live stream
validation next.

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

Cargo.lock

@@ -2774,6 +2774,7 @@ dependencies = [
  "ffmpeg-next",
  "mdns-sd",
  "opus",
+ "pf-ffvk",
  "pipewire",
  "punktfunk-core",
  "rustls",
@@ -2821,6 +2822,7 @@ dependencies = [
  "ash",
  "async-channel",
  "pf-client-core",
+ "pf-ffvk",
  "punktfunk-core",
  "sdl3",
  "tracing",