feat(host/windows): seal the host↔driver channels (frame + gamepad, proto v2)

Frame ring (pf-vdisplay) and both gamepad SHM channels move off named Global\
objects (openable by any sibling LocalService) to UNNAMED sections/events whose
handles the host DuplicateHandles into the driver's verified WUDFHost with least
access — frame delivery over the SYSTEM+admins-only IOCTL_SET_FRAME_CHANNEL,
pads over a 32-byte named bootstrap mailbox (pid + handle value only, DoS-bounded;
HID minidrivers have no control device). Driver-validated pad_index kills
cross-pad redirects; v1↔v2 mixes fail closed with diagnosis logs on both sides.
Sibling-LocalService denial proven empirically (design/idd-push-security.md,
design/gamepad-channel-sealing.md).

Driver-side raw ops now live behind pf-umdf-util (checked shm accessors, the
forbid(unsafe_code) ChannelClient state machine, WDF request tokens) — the pad
drivers' logic is 100% safe Rust; whole drivers workspace clippy-gated in CI.

driver install --gamepad now sweeps SWD\punktfunk phantom devnodes: a re-created
SwDevice REVIVES the old devnode with its previously-bound driver (never
re-ranks), so an upgrade otherwise leaves the old driver serving — or, across
the v1→v2 fence, a dead pad (found live on the RTX box).

On-glass validated on the RTX 4090 box: frame path 7007 frames p50 2.06 ms
cross-machine; DualSense + XUSB "sealed pad channel mapped"/proto=2 attach via
both the test harness and a real streaming session; phantom-sweep repro.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packaging/windows/drivers/pf-vdisplay/src/direct_3d_device.rs

@@ -123,10 +123,10 @@ static DEVICE_POOL: Mutex<Option<(i64, Arc<Direct3DDevice>)>> = Mutex::new(None)
 pub fn pooled_device(luid: LUID) -> Option<Arc<Direct3DDevice>> {
     let key = (i64::from(luid.HighPart) << 32) | i64::from(luid.LowPart);
     let mut pool = DEVICE_POOL.lock().ok()?;
-    if let Some((k, dev)) = pool.as_ref() {
-        if *k == key {
-            return Some(dev.clone());
-        }
+    if let Some((k, dev)) = pool.as_ref()
+        && *k == key
+    {
+        return Some(dev.clone());
     }
     match Direct3DDevice::init(luid) {
         Ok(d) => {