style(windows): rustfmt install.rs to unbreak cargo fmt --all --check

The pnputil /add-driver call in windows/install.rs was committed unwrapped;
`cargo fmt --all --check` (which checks cfg(windows) files too) flagged it and
failed the `rust` CI job at the Format step, skipping clippy/build/test. Apply
rustfmt — no behavior change. Clears the way to cut the v0.2.0 release from
green main.

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

crates/punktfunk-host/src/windows/install.rs

@@ -126,7 +126,10 @@ fn install_pf_vdisplay(dir: &Path) -> Result<()> {
         );
     }
     // Stage + bind the driver (idempotent; re-staging the same .inf is harmless).
-    if run_quiet("pnputil", &["/add-driver", &inf.to_string_lossy(), "/install"]) {
+    if run_quiet(
+        "pnputil",
+        &["/add-driver", &inf.to_string_lossy(), "/install"],
+    ) {
         println!("pnputil /add-driver pf_vdisplay.inf /install ok");
     } else {
         eprintln!("warning: pnputil /add-driver /install failed (driver may not have installed)");