ci(windows-drivers): workspace-level WDK driver-model (fixes wdk-sys build)

wdk-sys build script: "missing field driver-model" deserializing
workspace_metadata[wdk] — a workspace build reads the model from the WORKSPACE
metadata, not the package. Set [workspace.metadata.wdk.driver-model] = UMDF 2.31
(all our drivers are UMDF 2.x incl. pf-vdisplay IddCx). Past the Cargo.lock fix.

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

packaging/windows/drivers/Cargo.toml

@@ -21,8 +21,13 @@ wdk-sys = "0.5.1"
 wdk-build = "0.5.1"
 pf-vdisplay-proto = { path = "../../../crates/pf-vdisplay-proto" }
 
-# windows-drivers-rs marks a driver workspace with this section (per-package driver-model overrides it).
-[workspace.metadata.wdk]
+# wdk-sys's build script reads the WDK driver-model from the WORKSPACE metadata (a workspace build can't
+# know which member it's building for). All our drivers are UMDF 2.x (incl. pf-vdisplay's IddCx), so set
+# it once here; a member needing a different model would get its own [package.metadata.wdk.driver-model].
+[workspace.metadata.wdk.driver-model]
+driver-type = "UMDF"
+umdf-version-major = 2
+target-umdf-version-minor = 31
 
 [profile.dev]
 panic = "abort"