fix(host/windows): install the GPU-preference hook at process start (before any DXGI)

The win32u hook only works if it patches before DXGI caches the hybrid preference.
It was installed in DuplCapturer::open (first capture), but the SudoVDA
render-adapter selection creates a DXGI factory during virtual-display setup —
seconds earlier — so the preference was already cached and the hook had no effect
(churn persisted; log showed "render adapter chosen" at :02, "hook installed" at
:04). Call install_gpu_pref_hook() at the top of real_main(), before any command
runs, so it beats the first DXGI factory. (open() still calls it too; Once makes
the earliest call win.) Also fix the cosmetic function-cast-as-integer warning.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/punktfunk-host/src/main.rs

@@ -75,6 +75,13 @@ fn real_main() -> Result<()> {
         punktfunk_core::ABI_VERSION
     );
 
+    // Install Apollo's win32u GPU-preference hook BEFORE anything touches DXGI (the SudoVDA
+    // render-adapter selection creates a DXGI factory during virtual-display setup, well before
+    // capture). On a hybrid-GPU box this stops DXGI from reparenting the virtual output off the
+    // capture GPU — the ACCESS_LOST churn fix. Idempotent (Once); harmless on non-hybrid boxes.
+    #[cfg(target_os = "windows")]
+    crate::capture::dxgi::install_gpu_pref_hook();
+
     match args.first().map(String::as_str) {
         // GameStream host control plane (P1.1: mDNS + serverinfo) + management API, and (with
         // --native) the native punktfunk/1 host in the same process — the unified host.