feat(host/windows): resident virtual HID mouse (pf-mouse UMDF minidriver)

Headless Windows hosts (no dongle) stream an INVISIBLE cursor: with no
pointing device present win32k reports SM_MOUSEPRESENT=0 and DWM never
composites a pointer into the pf-vdisplay frame, even though SendInput
moves it. Keep ONE virtual HID mouse devnode alive for the host's
lifetime — the Sunshine/Parsec-class fix, zero client changes.

- pf-mouse: UMDF2 HID minidriver, one fixed identity (PF:MO 5046:4D4F,
  obviously virtual, nothing fingerprints it), one 8-byte input report
  (5 buttons + absolute 15-bit X/Y + wheel + AC-pan). Transport is the
  sealed pad channel verbatim (Global\pfmouse-boot-0 mailbox + unnamed
  MouseShm DATA section) so pf-umdf-util's audited layer serves it
  unchanged; report delivery is event-driven (idle = no HID traffic).
- host: inject::mouse_windows — VirtualMouse (SwDeviceCreate'd devnode +
  channel), ensure_resident() keeper thread started by every
  InjectorService (process-wide, PUNKTFUNK_NO_VIRTUAL_MOUSE opts out),
  vmouse-spike on-glass validation (cursor sweep via HID reports).
- proto: mouse module (magic, boot-name, identity, report layout,
  unit-tested input_report packing).
- SwDeviceProfile grows container_tag so the mouse's ContainerId family
  (PFMO) never groups with a pad's (PFDS) in the Devices UI.
- packaging: pf-mouse rides the gamepad-driver build + install pipeline
  (build-gamepad-drivers.ps1, windows-drivers.yml, driver install
  --gamepad picks up every staged .inf).

On-glass validated on winbox: devnode + HID child bind, SM_MOUSEPRESENT=1
with no physical mouse, cursor sweeps via HID reports (vmouse-spike).

This work was implemented in a parallel session; committed here as the
build prerequisite for the HID compose kick that follows.

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

packaging/windows/drivers/pf-mouse/build.rs

@@ -0,0 +1,12 @@
+// Copyright (c) Microsoft Corporation
+// License: MIT OR Apache-2.0
+
+//! Build script for the `sample-umdf-driver` crate.
+//!
+//! Based on the [`wdk_build::Config`] parsed from the build tree, this build
+//! script will provide `Cargo` with the necessary information to build the
+//! driver binary (ex. linker flags)
+
+fn main() -> Result<(), wdk_build::ConfigError> {
+    wdk_build::configure_wdk_binary_build()
+}