feat(host/windows): SDR-while-secure — drop SudoVDA out of HDR on Winlogon so DDA captures it

When the DDA-on-secure path is enabled (PUNKTFUNK_SECURE_DDA=1), the mux now
toggles the SudoVDA's advanced-color (HDR) state via the CCD API
(sudovda::set_advanced_color → DisplayConfigSetDeviceInfo +
DISPLAYCONFIG_SET_ADVANCED_COLOR_STATE): on entering the secure (Winlogon)
desktop it disables HDR so the lock/UAC renders SDR/composed (no fullscreen
independent-flip → DDA can duplicate it instead of storming ACCESS_LOST/black),
opens DDA fresh on the now-SDR output; on returning to normal it re-enables HDR
and rebuilds the helper so WGC re-detects the restored colorspace.

Also debounce the DesktopWatcher (publish a Default↔Winlogon change only after it
is stable ~80ms) so transient flaps during the transition don't thrash the mux.

Default (no flag) is unchanged: WGC stays live through a lock, no DDA switch.

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

crates/punktfunk-host/src/vdisplay/sudovda.rs

@@ -22,8 +22,10 @@ use windows::Win32::Devices::DeviceAndDriverInstallation::{
     SP_DEVICE_INTERFACE_DATA, SP_DEVICE_INTERFACE_DETAIL_DATA_W,
 };
 use windows::Win32::Devices::Display::{
-    DisplayConfigGetDeviceInfo, GetDisplayConfigBufferSizes, QueryDisplayConfig,
-    DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME, DISPLAYCONFIG_MODE_INFO, DISPLAYCONFIG_PATH_INFO,
+    DisplayConfigGetDeviceInfo, DisplayConfigSetDeviceInfo, GetDisplayConfigBufferSizes,
+    QueryDisplayConfig, DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME,
+    DISPLAYCONFIG_DEVICE_INFO_SET_ADVANCED_COLOR_STATE, DISPLAYCONFIG_MODE_INFO,
+    DISPLAYCONFIG_PATH_INFO, DISPLAYCONFIG_SET_ADVANCED_COLOR_STATE,
     DISPLAYCONFIG_SOURCE_DEVICE_NAME, QDC_ONLY_ACTIVE_PATHS,
 };
 use windows::Win32::Foundation::{CloseHandle, HANDLE, LUID};
@@ -216,6 +218,55 @@ pub(crate) unsafe fn resolve_gdi_name(target_id: u32) -> Option<String> {
     None
 }
 
+/// Toggle the SudoVDA target's advanced-color (HDR) state via the CCD API. Disabling HDR while on the
+/// secure (Winlogon) desktop makes it render SDR/composed so DXGI Desktop Duplication can capture it
+/// (the HDR fullscreen independent-flip otherwise storms `ACCESS_LOST` → black); re-enable on return so
+/// WGC keeps HDR on the normal desktop. Returns true on a successful `DisplayConfigSetDeviceInfo`.
+pub(crate) unsafe fn set_advanced_color(target_id: u32, enable: bool) -> bool {
+    let mut np = 0u32;
+    let mut nm = 0u32;
+    if GetDisplayConfigBufferSizes(QDC_ONLY_ACTIVE_PATHS, &mut np, &mut nm).is_err() {
+        return false;
+    }
+    let mut paths = vec![DISPLAYCONFIG_PATH_INFO::default(); np as usize];
+    let mut modes = vec![DISPLAYCONFIG_MODE_INFO::default(); nm as usize];
+    if QueryDisplayConfig(
+        QDC_ONLY_ACTIVE_PATHS,
+        &mut np,
+        paths.as_mut_ptr(),
+        &mut nm,
+        modes.as_mut_ptr(),
+        None,
+    )
+    .is_err()
+    {
+        return false;
+    }
+    for p in paths.iter().take(np as usize) {
+        if p.targetInfo.id == target_id {
+            let mut s = DISPLAYCONFIG_SET_ADVANCED_COLOR_STATE::default();
+            s.header.r#type = DISPLAYCONFIG_DEVICE_INFO_SET_ADVANCED_COLOR_STATE;
+            s.header.size = size_of::<DISPLAYCONFIG_SET_ADVANCED_COLOR_STATE>() as u32;
+            s.header.adapterId = p.targetInfo.adapterId;
+            s.header.id = p.targetInfo.id;
+            s.Anonymous.value = enable as u32; // bit 0 = enableAdvancedColor
+            let rc = DisplayConfigSetDeviceInfo(&mut s.header);
+            tracing::info!(
+                target_id,
+                enable,
+                rc,
+                "SudoVDA set advanced-color (HDR) state"
+            );
+            return rc == 0;
+        }
+    }
+    tracing::warn!(
+        target_id,
+        "set_advanced_color: target not found in active paths"
+    );
+    false
+}
+
 /// Force the freshly-added SudoVDA monitor to the client's exact `WxH@Hz`. The ADD IOCTL only
 /// ADVERTISES the mode; Windows otherwise activates an IDD target at a 1280x720 default, so the
 /// ACTIVE mode (what DXGI Desktop Duplication captures) must be set explicitly. CDS_TEST first so a