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-dualsense/README.md

@@ -85,6 +85,9 @@ silently breaks them:
 
 - **Multi-pad** works via `UmdfHostProcessSharing=ProcessSharingDisabled` — each pad gets its own
   WUDFHost (so the per-instance statics don't collide), and the driver reads its pad index from the
-  device Location (`WdfDeviceAllocAndQueryProperty`) to map its own `*-shm-<index>` channel.
+  device Location (`WdfDeviceAllocAndQueryProperty`) to poll its own `*-boot-<index>` bootstrap
+  mailbox (the DATA section itself is unnamed — the sealed pad channel,
+  `design/gamepad-channel-sealing.md` — and its `pad_index` is validated against this index on
+  attach).
 - Port of the WDK `vhidmini2` UMDF2 sample; the DualSense identity + 273-byte descriptor + feature
   blobs `0x05`/`0x09`/`0x20` come from `crates/punktfunk-host/src/inject/dualsense.rs`.