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/build.rs

@@ -0,0 +1,18 @@
+//! Embed the Windows version-info + icon resources into `punktfunk-client.exe`. The icon drives
+//! Explorer / Alt-Tab / the unpackaged taskbar, and `app::run` stamps it onto the WinUI window's
+//! title bar via `WM_SETICON` (the MSIX taskbar/Start icons come from the package assets instead).
+
+fn main() {
+    // cfg(windows) is the HOST (skips the Linux/macOS workspace stub build); CARGO_CFG_WINDOWS
+    // is the TARGET (both the x64 and the cross-compiled ARM64 Windows builds pass).
+    #[cfg(windows)]
+    if std::env::var_os("CARGO_CFG_WINDOWS").is_some() {
+        let icon = "../../packaging/windows/branding/punktfunk.ico";
+        println!("cargo:rerun-if-changed={icon}");
+        winresource::WindowsResource::new()
+            // Ordinal 1 — app/mod.rs loads it by this id for WM_SETICON.
+            .set_icon_with_id(icon, "1")
+            .compile()
+            .expect("embed windows icon resource");
+    }
+}