feat(windows-drivers): pf-vdisplay STEP 0 scaffold + std-under-UMDF link gate

M1 step 2 begins. Add the wdk-iddcx (lib, re-exports wdk_sys::iddcx) + pf-vdisplay
(cdylib) workspace members. pf-vdisplay STEP 0 = DriverEntry + WdfDeviceCreate
skeleton + a #[used] _std_link_gate forcing std::thread + OwnedHandle to link, so
the build proves the std surface resolves under the wdk-build UMDF link settings
(kernel32 is /NODEFAULTLIB - std must come via OneCoreUAP). If std fails to link
here, the SwapChainProcessor worker-thread design needs a CreateThread shim before
any callback work (port-plan critique gap #9).

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

packaging/windows/drivers/wdk-iddcx/src/lib.rs

@@ -0,0 +1,11 @@
+//! Safe-ish typed wrappers over the wdk-sys IddCx DDIs, dispatched through the `IddFunctions` table
+//! (indexed by `_IDDFUNCENUM::<Name>TableIndex`, with `IddDriverGlobals` as the implicit first arg) —
+//! the same model wdk-sys uses for WDF. Graduates the proven dispatch from `wdk-probe/src/iddcx_rt.rs`
+//! (M1 step 1) into the crate the pf-vdisplay driver builds on.
+//!
+//! STEP 0: re-export the wdk-sys `iddcx` module so the crate + the `iddcx` feature resolve in the
+//! workspace. STEP 1 adds the 11 typed DDI wrappers (one fixed `(_IDDFUNCENUM index, PFN_*)` pair per
+//! site) + `is_nt_error`/`other_is_error` + the inbound `PFN_IDD_CX_*` callback-type re-exports.
+#![no_std]
+
+pub use wdk_sys::iddcx;