refactor: resolved cross-platform build warnings and add windows-sys features

- Add conditional attributes to silence dead-code warnings on platform-specific code and fields.
- Update target dependencies in pi-walker/Cargo.toml with explicit windows-sys feature sets.
- Simplify time cast expressions in linux_reflink and rcopy modules.

crates/pi-iso/src/linux_reflink.rs

@@ -248,14 +248,8 @@ mod imp {
 
 	fn set_times_nofollow(path: &Path, meta: &fs::Metadata) -> std::io::Result<()> {
 		let times = [
-			libc::timespec {
-				tv_sec:  meta.atime() as libc::time_t,
-				tv_nsec: meta.atime_nsec() as libc::c_long,
-			},
-			libc::timespec {
-				tv_sec:  meta.mtime() as libc::time_t,
-				tv_nsec: meta.mtime_nsec() as libc::c_long,
-			},
+			libc::timespec { tv_sec: meta.atime() as _, tv_nsec: meta.atime_nsec() as libc::c_long },
+			libc::timespec { tv_sec: meta.mtime() as _, tv_nsec: meta.mtime_nsec() as libc::c_long },
 		];
 		let c_path = CString::new(path.as_os_str().as_bytes())?;
 		// SAFETY: `c_path` and `times` live until the syscall returns; the

crates/pi-iso/src/rcopy.rs

@@ -413,11 +413,10 @@ fn filetime_set(path: &Path, mtime: std::time::SystemTime) -> std::io::Result<()
 	let dur = mtime
 		.duration_since(std::time::UNIX_EPOCH)
 		.map_err(std::io::Error::other)?;
-	let times =
-		[libc::timespec { tv_sec: dur.as_secs() as libc::time_t, tv_nsec: 0 }, libc::timespec {
-			tv_sec:  dur.as_secs() as libc::time_t,
-			tv_nsec: dur.subsec_nanos() as libc::c_long,
-		}];
+	let times = [libc::timespec { tv_sec: dur.as_secs() as _, tv_nsec: 0 }, libc::timespec {
+		tv_sec:  dur.as_secs() as _,
+		tv_nsec: dur.subsec_nanos() as libc::c_long,
+	}];
 	let c_path = std::ffi::CString::new(path.as_os_str().as_bytes())?;
 	// SAFETY: `c_path` and `times` outlive the syscall; the kernel does
 	// not retain the pointers.