fix(windows-host): self-heal the hostless-zombie pf-vdisplay device (adapter cycle + re-probe)

Fault-injection on-glass showed a killed/crashed WUDFHost leaves the devnode
"started" but HOSTLESS: PnP Status OK, no WUDFHost process, zero device-
interface instances — is_available() then fails every future session at the
vdisplay::open gate (and a reopen inside VdisplayDriver::open finds nothing),
until something cycles the device. Port reset-pf-vdisplay.ps1's adapter
disable→enable step in-process (restart_vdisplay_device): the open gate now
uses ensure_available() (cycle once + bounded re-probe; a genuinely
uninstalled driver — no adapter devnode — still fails fast), and
VdisplayDriver::open retries open_device over a short arrival window after a
cycle, covering the manager's reopen path too.

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

crates/punktfunk-host/src/vdisplay.rs

@@ -646,8 +646,10 @@ pub fn open(compositor: Compositor) -> Result<Box<dyn VirtualDisplay>> {
         // The pf-vdisplay all-Rust IddCx driver is the sole virtual-display backend (the legacy SudoVDA
         // fallback was removed — its driver is no longer shipped). The compositor arg is moot on Windows.
         let _ = compositor;
+        // `ensure_available` self-heals the hostless-zombie state a WUDFHost crash leaves (adapter
+        // devnode present, interface gone): one device cycle + re-probe before giving up.
         anyhow::ensure!(
-            pf_vdisplay::is_available(),
+            pf_vdisplay::ensure_available(),
             "pf-vdisplay driver interface not found — the pf-vdisplay IddCx driver is not installed or \
              not loaded (the host installer bundles it; reinstall or check the driver state)"
         );