feat(windows): pf-vdisplay-proto — owned host<->driver ABI crate (rewrite M0)

First foundation of the Windows-host rewrite (docs/windows-host-rewrite.md): a
self-contained, no_std + bytemuck crate that defines the host<->driver binary
contract ONCE — the control-plane IOCTLs (add/remove/set-render-adapter/ping/
get-info/clear-all) and the IDD-push frame transport (SharedHeader, the
(gen<<40|seq<<8|slot) FrameToken, the Global\pfvd-* name scheme, driver-status
codes). Previously these were hand-duplicated byte-for-byte across
idd_push.rs/frame_transport.rs and sudovda.rs/control.rs with only "must match"
comments; here const size-asserts + bytemuck round-trips make any drift a COMPILE
error.

Clean break from SudoVDA: a freshly-minted interface GUID (not e5bcc234), a
contiguous 0x900 op space (not the gappy 0x800/0x888/0x8FF), a u64 session id (not
the 16-byte GUID + pid-mangling), a single u32 protocol version. Self-contained
(no workspace inheritance, no Windows deps) so the out-of-workspace driver build
graph can path-dep it identically. 7 tests green on Linux; clippy + fmt clean.

Also lands the full rewrite plan in docs/windows-host-rewrite.md (decisions:
greenfield; IDD-push primary incl. secure desktop, WGC+DDA demoted to fallbacks;
unify drivers on windows-drivers-rs + solve /INTEGRITYCHECK; keep GameStream,
default secure).

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

crates/pf-vdisplay-proto/Cargo.toml

@@ -0,0 +1,19 @@
+# Shared host<->driver binary contract for the punktfunk pf-vdisplay virtual display.
+#
+# Deliberately self-contained (no `*.workspace = true` inheritance, no Windows deps): this crate is a
+# path dependency of BOTH the host workspace (crates/punktfunk-host) AND the out-of-workspace driver
+# workspace (packaging/windows/drivers/), so it must resolve identically from either build graph. It is
+# `no_std` (+ alloc) and platform-neutral; the GUID/LUID are plain integers each side converts to its
+# own OS type. Defining every wire struct ONCE here — with `const` size/offset asserts + bytemuck
+# round-trips — makes host<->driver ABI drift a COMPILE error instead of a silent frame/IOCTL corruption.
+[package]
+name = "pf-vdisplay-proto"
+version = "0.0.1"
+edition = "2021"
+rust-version = "1.82"
+license = "MIT OR Apache-2.0"
+description = "Shared host<->driver binary contract for the punktfunk pf-vdisplay virtual display (control IOCTLs + IDD-push frame transport)."
+publish = false
+
+[dependencies]
+bytemuck = { version = "1.19", features = ["derive"] }