fix(host/windows): don't 2-way-split-encode Main10 — it's SLOWER on Ada (fixes broken HDR animations)

The "broken animations in HDR" was an encode-throughput cliff, not the ACCESS_LOST churn. Measured at
5120x1440@240 HEVC Main10 on the RTX 4090: forced 2-way split-encode = 7.6 ms/frame (~131 fps, well
over the 4.17 ms/240fps budget → choppy), while SINGLE engine = 2.8-3.9 ms/frame (~256-357 fps, fits
240). The split/merge overhead dominates for 10-bit; a single Ada NVENC engine already handles 5K@240
Main10 comfortably. So the split decision now forces DISABLE for Main10 (bit_depth >= 10), keeping the
existing forced-2 only for 8-bit above 1 Gpix/s. PUNKTFUNK_SPLIT_ENCODE still overrides. Added a
split-mode log line.

Validated live on the 4090: encode_us_p50 7.6 ms → 3.9 ms at 5K240 HDR with no env override.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/punktfunk-client-windows/src/main.rs

@@ -0,0 +1,150 @@
+//! `punktfunk-client` — the native Windows punktfunk/1 client.
+//!
+//! Pure Rust: `NativeClient` linked as a crate (no C ABI, like the GTK Linux client) ·
+//! FFmpeg decode · WASAPI audio · SDL3 gamepads · a winit + Direct3D11 present surface. The
+//! trust surface mirrors the other native clients: persistent identity, TOFU prompt with the
+//! host fingerprint, SPAKE2 PIN pairing.
+//!
+//! Until the UI shell lands, the binary runs **headless** (`--connect host[:port]`): connect,
+//! decode, play audio, and print per-second stats — the Windows analogue of
+//! `punktfunk-client-rs`, for validating the protocol/decode path against a live host.
+
+#[cfg(windows)]
+mod audio;
+#[cfg(windows)]
+mod discovery;
+#[cfg(windows)]
+mod session;
+#[cfg(windows)]
+mod trust;
+#[cfg(windows)]
+mod video;
+
+#[cfg(windows)]
+fn main() {
+    use punktfunk_core::config::{CompositorPref, GamepadPref, Mode};
+    use std::time::{Duration, Instant};
+
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| "info".into()),
+        )
+        .init();
+
+    let args: Vec<String> = std::env::args().collect();
+    let arg = |name: &str| -> Option<String> {
+        args.iter()
+            .position(|a| a == name)
+            .and_then(|i| args.get(i + 1))
+            .cloned()
+    };
+
+    let Some(target) = arg("--connect") else {
+        eprintln!(
+            "punktfunk-client (headless): --connect host[:port] [--pin HEX] [--mode WxHxHz] \
+             [--bitrate MBPS] [--mic]\n\
+             The windowed UI is not wired yet; this runs the protocol/decode path headless."
+        );
+        std::process::exit(2);
+    };
+    let (host, port) = match target.rsplit_once(':') {
+        Some((a, p)) => (a.to_string(), p.parse().unwrap_or(9777)),
+        None => (target.clone(), 9777u16),
+    };
+    let mode = arg("--mode")
+        .and_then(|m| {
+            let mut it = m.split(['x', 'X']);
+            Some(Mode {
+                width: it.next()?.parse().ok()?,
+                height: it.next()?.parse().ok()?,
+                refresh_hz: it.next()?.parse().ok()?,
+            })
+        })
+        .unwrap_or(Mode {
+            width: 1280,
+            height: 720,
+            refresh_hz: 60,
+        });
+    let pin = arg("--pin").and_then(|h| trust::parse_hex32(&h));
+    let bitrate_kbps = arg("--bitrate")
+        .and_then(|b| b.parse::<u32>().ok())
+        .map(|m| m * 1000)
+        .unwrap_or(0);
+    let mic_enabled = args.iter().any(|a| a == "--mic");
+
+    let identity = match trust::load_or_create_identity() {
+        Ok(i) => i,
+        Err(e) => {
+            eprintln!("client identity: {e:#}");
+            std::process::exit(1);
+        }
+    };
+
+    tracing::info!(%host, port, ?mode, tofu = pin.is_none(), "connecting (headless)");
+    let handle = session::start(session::SessionParams {
+        host,
+        port,
+        mode,
+        compositor: CompositorPref::Auto,
+        gamepad: GamepadPref::Auto,
+        bitrate_kbps,
+        mic_enabled,
+        pin,
+        identity,
+    });
+
+    // Headless consumer: drain events + frames, print stats, run until the host ends or
+    // ~60 s elapse (the harness bound). Frames are counted and dropped (no present yet).
+    let deadline = Instant::now() + Duration::from_secs(60);
+    let mut frames_seen = 0u64;
+    loop {
+        while let Ok(ev) = handle.events.try_recv() {
+            match ev {
+                session::SessionEvent::Connected {
+                    mode, fingerprint, ..
+                } => tracing::info!(
+                    ?mode,
+                    fp = %trust::hex(&fingerprint),
+                    "connected"
+                ),
+                session::SessionEvent::Stats(s) => tracing::info!(
+                    fps = format!("{:.0}", s.fps),
+                    mbps = format!("{:.1}", s.mbps),
+                    decode_ms = format!("{:.2}", s.decode_ms),
+                    lat_ms = format!("{:.2}", s.latency_ms),
+                    frames_seen,
+                    "stats"
+                ),
+                session::SessionEvent::Failed { msg, .. } => {
+                    tracing::error!(%msg, "connect failed");
+                    return;
+                }
+                session::SessionEvent::Ended(err) => {
+                    tracing::info!(reason = err.as_deref().unwrap_or("done"), "session ended");
+                    return;
+                }
+            }
+        }
+        while handle.frames.try_recv().is_ok() {
+            frames_seen += 1;
+        }
+        if Instant::now() > deadline {
+            tracing::info!(frames_seen, "harness deadline — stopping");
+            handle.stop.store(true, std::sync::atomic::Ordering::SeqCst);
+            return;
+        }
+        std::thread::sleep(Duration::from_millis(2));
+    }
+}
+
+/// Win32/Direct3D11/WASAPI/SDL3 are Windows turf; this stub keeps `cargo build --workspace`
+/// green on Linux/macOS (the other native clients live in crates/punktfunk-client-linux and
+/// clients/apple).
+#[cfg(not(windows))]
+fn main() {
+    eprintln!(
+        "punktfunk-client-windows is Windows-only — the Linux client lives in \
+         crates/punktfunk-client-linux, the macOS client in clients/apple"
+    );
+    std::process::exit(2);
+}