feat(host/windows): ViGEm rumble back-channel + Windows clippy clean

Wire the host→client rumble path on Windows, the analogue of the Linux
uinput EV_FF read loop: a game's force-feedback on the virtual Xbox 360
pad is delivered by ViGEm's notification API (`request_notification` →
`spawn_thread`, gated by the crate's `unstable_xtarget_notification`
feature). A per-pad background thread stores the latest motor levels;
`pump_rumble` relays changes to the client on the universal 0xCA plane
(motors scaled 0..255 → 0..65535). Dropping the target aborts the
notification, so the thread exits with the session. Live verification
still needs a physical pad.

Also fix the Windows backends' clippy debt — these modules are cfg-
excluded from Linux CI, so `clippy -D warnings` never saw them, and the
VM's rustc 1.96 clippy is stricter on shared code than the CI image:
- dxgi: manual checked division → checked_div().map_or
- sendinput: `x = x | y` → `x |= y`
- sudovda: `.then(|| ptr)` → `.then_some(ptr)`
- m3 pick_compositor: drop the needless early return (match form)
- m3 resolve_compositor: Windows arm is a tail expr, not `return`

All Windows backends now build + clippy clean (default and --features
nvenc); Linux unaffected (fmt/clippy/check green).

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

crates/punktfunk-host/src/m3.rs

@@ -1520,12 +1520,10 @@ fn pick_compositor(
     available: &[crate::vdisplay::Compositor],
     detected: Option<crate::vdisplay::Compositor>,
 ) -> Option<crate::vdisplay::Compositor> {
-    if let Some(want) = crate::vdisplay::Compositor::from_pref(pref) {
-        if available.contains(&want) {
-            return Some(want);
-        }
+    match crate::vdisplay::Compositor::from_pref(pref) {
+        Some(want) if available.contains(&want) => Some(want),
+        _ => detected,
     }
-    detected
 }
 
 /// Resolve the client's compositor preference to a concrete backend (the I/O shell around
@@ -1539,7 +1537,7 @@ fn resolve_compositor(pref: CompositorPref) -> Result<crate::vdisplay::Composito
     #[cfg(target_os = "windows")]
     {
         let _ = pref;
-        return Ok(Compositor::Kwin);
+        Ok(Compositor::Kwin)
     }
     #[cfg(not(target_os = "windows"))]
     {