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>

Cargo.toml

@@ -3,6 +3,7 @@ resolver = "2"
 members = [
     "crates/punktfunk-core",
     "crates/punktfunk-host",
+    "crates/pf-vdisplay-proto",
     "clients/probe",
     "clients/linux",
     "clients/windows",