feat(clients/windows): all-vendor video pipeline rewrite + app icon + hosts-page tiles

Decode+present rewrite (first real pixels on glass for this client):

- Decode: FFmpeg D3D11VA on NVIDIA/AMD/Intel. get_format now only returns
  AV_PIX_FMT_D3D11 and lets libavcodec build the decode pool from
  hw_device_ctx (hand-built frames contexts failed three different ways:
  NVIDIA rejects DECODER|SHADER_RESOURCE arrays, BindFlags=0 fails texture
  creation, Intel rejects non-128-aligned HEVC surfaces at the first
  SubmitDecoderBuffers). A DXVA profile probe before the hwdevice commits
  hardware-vs-software up front instead of burning the opening IDR;
  extra_hw_frames covers the frames the client holds.
- Present: the decoded slice is copied with ONE display-size-boxed
  CopySubresourceRegion (a planar slice is a single subresource in D3D11;
  the old two-copy D3D12-style code silently no-opped - the black screen)
  into a sampleable NV12/P010 texture, per-plane SRVs + YUV->RGB shaders.
- New dedicated render thread (render.rs): presenting is decoupled from the
  XAML thread; frame-latency-waitable swapchain + SetMaximumFrameLatency(1),
  newest-wins drain after the wait, crossbeam frame channel with pts for a
  capture->presented p50 log.
- HiDPI: pixel-sized buffers + SetMatrixTransform(96/dpi) - was blurry at
  125/150 % scaling.
- Software fallback now feeds the same shaders (swscale -> NV12/P010 planes
  -> two dynamic plane textures); ps_rgba/X2BGR10 path deleted, hw/sw colour
  math identical.
- Adapter selection for hybrid boxes: PUNKTFUNK_ADAPTER > the window's
  monitor's adapter > default; PUNKTFUNK_D3D_DEBUG=1 debug layer.
- Session pump: request_keyframe at start and on hw->sw demotion (infinite
  GOP would otherwise sit on a black screen).

Validated live on the Arc Pro + RTX 3500 Ada laptop against the local
Windows host: 60 fps D3D11VA on both vendors, software path, GUI on glass.

Also: embedded app icon (build.rs winresource + WM_SETICON, MSIX
Square44x44 targetsize assets, pack-msix stages them) and the hosts-page
tile rework (tap-to-connect tiles with sibling overflow menu - fixes
forget-also-connects - in-tile rename editor, add-host modal via root state).

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

clients/windows/Cargo.toml

@@ -39,6 +39,8 @@ windows = { git = "https://github.com/microsoft/windows-rs", rev = "b4129fcc1ae8
     "Win32_Graphics_Gdi",
     "Win32_System_Console",
     "Win32_System_LibraryLoader",
+    "Win32_System_Threading",
+    "Win32_UI_HiDpi",
     "Win32_UI_Input_KeyboardAndMouse",
     "Win32_UI_WindowsAndMessaging",
 ] }
@@ -57,8 +59,15 @@ sdl3 = { version = "0.18", features = ["build-from-source", "hidapi"] }
 
 mdns-sd = "0.20"
 async-channel = "2"
+# The decoded-frame channel (session pump → render thread): crossbeam because the render loop
+# blocks with `recv_timeout`, which async-channel has no sync analogue of.
+crossbeam-channel = "0.5"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 anyhow = "1"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+
+# Embeds the app icon as an exe resource (build.rs) — Windows hosts only (rc.exe from the SDK).
+[target.'cfg(windows)'.build-dependencies]
+winresource = "0.1"