feat(windows-drivers): pf-vdisplay STEP 2 — IddCx device skeleton

DriverEntry -> driver_add builds the full IDD_CX_CLIENT_CONFIG (14 IddCx callbacks +
PnP EvtDeviceD0Entry, all stubs with correct PFN signatures) sized via the ported
IDD_STRUCTURE_SIZE! (size.rs), runs IddCxDeviceInitConfig -> WdfDeviceCreate ->
WdfDeviceCreateDeviceInterface(the owned pf-vdisplay GUID, not SudoVDA) ->
IddCxDeviceInitialize. callbacks.rs has all 14 + device_d0_entry; query_target_info
implements HIGH_COLOR_SPACE. edid.rs salvaged verbatim from the oracle. proto gains
interface_guid_fields() (u128 -> Windows GUID fields). Links IddCxStub (the CI gate);
adapter/monitor/swapchain/IDD-push fill the stubs in STEP 3-6.

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

packaging/windows/drivers/pf-vdisplay/build.rs

@@ -1,6 +1,38 @@
-//! Emits the WDK link flags for the cdylib (wdk-build). STEP 0 needs only the WDF stub link + the
-//! `/INTEGRITYCHECK` that the CI step clears; `IddCxStub` (+ `IddMinimumVersionRequired`) is added in
-//! STEP 2 when the driver actually calls IddCx — see wdk-probe/build.rs for the glob recipe.
+//! WDK link flags for the cdylib (wdk-build) + `IddCxStub` (the driver calls IddCx DDIs via wdk-iddcx,
+//! and exports `IddMinimumVersionRequired`). `/INTEGRITYCHECK` (set by wdk-build) is cleared by the CI
+//! packaging step. Glob recipe matches wdk-probe/build.rs.
 fn main() -> Result<(), wdk_build::ConfigError> {
-    wdk_build::configure_wdk_binary_build()
+    wdk_build::configure_wdk_binary_build()?;
+    link_iddcx_stub();
+    Ok(())
+}
+
+/// Link `IddCxStub.lib`. It ships only under the SDK *version* that includes IddCx, at
+/// `Lib\<ver>\um\<arch>\iddcx\<iddcxver>\` — a newer base SDK alongside it lacks the `iddcx` subdir, so
+/// glob for the dir that actually contains the lib rather than trusting the max SDK version. x64 only.
+fn link_iddcx_stub() {
+    const ARCH: &str = "x64";
+    const ROOTS: [&str; 2] = [
+        r"C:\Program Files (x86)\Windows Kits\10\Lib",
+        r"C:\Program Files\Windows Kits\10\Lib",
+    ];
+    for root in ROOTS {
+        let Ok(versions) = std::fs::read_dir(root) else {
+            continue;
+        };
+        for ver in versions.flatten() {
+            let iddcx = ver.path().join("um").join(ARCH).join("iddcx");
+            let Ok(subdirs) = std::fs::read_dir(&iddcx) else {
+                continue;
+            };
+            for sub in subdirs.flatten() {
+                if sub.path().join("IddCxStub.lib").is_file() {
+                    println!("cargo:rustc-link-search={}", sub.path().display());
+                    println!("cargo:rustc-link-lib=static=IddCxStub");
+                    return;
+                }
+            }
+        }
+    }
+    panic!("IddCxStub.lib not found under any Windows Kits Lib\\<ver>\\um\\{ARCH}\\iddcx\\<iddcxver>\\");
 }