feat(clients/windows): screen-module restructure + parity features (speed test, native mode, capture UX)

Structure: split the 1400-line app.rs into per-screen app/ modules (mod=root/
router, hosts, connect, pair, speed, settings, licenses, stream, style) with
shared card/header/busy-page builders and setting_combo/toggle helpers; the
re-render rule (thread-driven state lives in root use_async_state, flows down
as props) is now documented at the module root.

Parity features the other clients already had:
- "Native display" resolves the real monitor mode at connect
  (MonitorFromWindow -> EnumDisplaySettingsW; was a hardcoded 1080p60)
- per-host network speed test: saved-host card button + a results screen
  (probe burst -> goodput/loss -> ~70% recommended bitrate applied in one
  tap; stale runs invalidated by generation) and `--headless --speed-test`;
  the bitrate setting becomes a free-form NumberBox so the recommendation
  round-trips
- forget host (ContentDialog confirm -> KnownHosts::remove_by_fp)
- settings: forwarded-controller picker (pads/pinned/set_pinned now wired),
  gamepad type, host compositor, capture-system-shortcuts; the previously
  dead Settings.compositor / inhibit_shortcuts are honored (shortcuts off =
  Alt+Tab/Alt+Esc/Ctrl+Esc/Win act locally)
- click-to-recapture after a Ctrl+Alt+Shift+Q release; the HUD hint tracks
  the live capture state

Perf: the input hook caches lock geometry (clip rect + contain-fit scale) at
engage instead of GetClientRect per WM_MOUSEMOVE; the audio jitter ring trims
via drain() and reuses the render scratch buffer.

Validated on the bare-metal box: --discover, synthetic-host loopback E2E
(TOFU -> clock skew -> HEVC negotiate -> D3D11VA init -> session end),
speed-test E2E, and the WinUI shell rendering in the console session via
PsExec (SSH/session-0 cannot create windows, pre-existing 0x80070005).

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

clients/windows/src/session.rs

@@ -80,6 +80,55 @@ pub struct SessionHandle {
     pub stop: Arc<AtomicBool>,
 }
 
+/// Blocking speed-test probe (the GUI's per-host "Test" and the `--headless --speed-test` CLI):
+/// a minimal identified connect (720p60 — the host builds a virtual output, but nothing is
+/// decoded), then `request_probe` (a 2 s burst up to the host's 3 Gbps ceiling) polled to
+/// completion. Run on a worker thread.
+pub fn run_speed_probe(
+    addr: &str,
+    port: u16,
+    fp_hex: Option<&str>,
+    identity: (String, String),
+) -> Result<punktfunk_core::client::ProbeOutcome, String> {
+    // Pin the saved/advertised fingerprint when we have one; a manual host measures over TOFU.
+    let pin = fp_hex.and_then(crate::trust::parse_hex32);
+    let c = NativeClient::connect(
+        addr,
+        port,
+        Mode {
+            width: 1280,
+            height: 720,
+            refresh_hz: 60,
+        },
+        CompositorPref::Auto,
+        GamepadPref::Auto,
+        0, // bitrate_kbps: host default
+        0, // video_caps: probe connect, nothing is decoded
+        2, // audio_channels: stereo baseline
+        crate::video::decodable_codecs(),
+        0,    // preferred_codec: no preference
+        None, // launch: no game
+        pin,
+        Some(identity),
+        Duration::from_secs(15),
+    )
+    .map_err(|e| format!("connect: {e:?}"))?;
+    c.request_probe(3_000_000, 2_000)
+        .map_err(|e| format!("probe: {e:?}"))?;
+    let deadline = Instant::now() + Duration::from_secs(10);
+    loop {
+        std::thread::sleep(Duration::from_millis(250));
+        if c.probe_result().done {
+            // Let the last UDP shards land before tearing down.
+            std::thread::sleep(Duration::from_millis(400));
+            return Ok(c.probe_result());
+        }
+        if Instant::now() > deadline {
+            return Err("probe timed out".to_string());
+        }
+    }
+}
+
 pub fn start(params: SessionParams) -> SessionHandle {
     let (ev_tx, ev_rx) = async_channel::unbounded();
     // Tiny frame queue, newest wins: force_send displaces the oldest when the UI lags.