fix(windows/vdisplay): QueryHardwareCursor3 + per-mode-commit cursor re-setup — M2c findings

Durable results of the M2c on-glass bring-up (.173, 2026-07-22):

- The base IddCxMonitorQueryHardwareCursor DDI slot is stubbed to
  STATUS_NOT_SUPPORTED on WDK 26100 — add the ...QueryHardwareCursor3
  wrapper (wdk-iddcx) and drain it instead; v3 X/Y are only meaningful
  when PositionValid, so a position-invalid tick keeps the prior position.
- Hardware-cursor setup is per-mode-commit: the OS silently reverts to a
  software cursor on every mode commit, so re-issue the setup on each
  swap-chain assignment (monitor::resetup_cursor, called from
  assign_swap_chain) or the query fails NOT_SUPPORTED forever.
- One caps definition for initial setup and re-setup, resting at XOR
  FULL: the query delivers ONLY alpha shapes in every configuration
  (all three ColorXorCursorSupport levels, event-driven and 30 Hz
  polled) — masked/monochrome cursors never arrive. FULL keeps the
  frame cursor-free for ALL cursor types; the full-fidelity shape comes
  from the session-side cursor source in the host
  (design/remote-desktop-sweep.md §8).
- Poll the query at ~30 Hz instead of pure event-wait: masked cursors
  never fire the data event, and the seqlock's position/visibility
  should stay fresh regardless.

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

packaging/windows/drivers/wdk-iddcx/src/lib.rs

@@ -151,6 +151,17 @@ iddcx_ddi!(
         out_args: *mut iddcx::IDARG_OUT_QUERY_HWCURSOR,
     ) @ IddCxMonitorQueryHardwareCursorTableIndex as PFN_IDDCXMONITORQUERYHARDWARECURSOR
 );
+iddcx_ddi!(
+    /// The v3 hardware-cursor drain — same input, richer output (adds `PositionValid` /
+    /// `PositionId` / `SdrWhiteLevel`). The base [`IddCxMonitorQueryHardwareCursor`] slot is
+    /// stubbed to `STATUS_NOT_SUPPORTED` on current IddCx (observed on-glass, WDK 26100), so
+    /// this is the live query DDI.
+    IddCxMonitorQueryHardwareCursor3(
+        monitor: iddcx::IDDCX_MONITOR,
+        in_args: *const iddcx::IDARG_IN_QUERY_HWCURSOR,
+        out_args: *mut iddcx::IDARG_OUT_QUERY_HWCURSOR3,
+    ) @ IddCxMonitorQueryHardwareCursor3TableIndex as PFN_IDDCXMONITORQUERYHARDWARECURSOR3
+);
 iddcx_ddi!(
     /// Set the preferred render adapter (LUID) for the virtual adapter.
     IddCxAdapterSetRenderAdapter(