Use golang.org/x/term for terminal width detection

Replace direct unix.IoctlGetWinsize() call with term.GetSize() for
cleaner API. No binary size change as x/sys remains an indirect
dependency.

main.go

@@ -11,7 +11,7 @@ import (
 
 	"github.com/go-git/go-git/v6"
 	"github.com/shirou/gopsutil/v4/process"
-	"golang.org/x/sys/unix"
+	"golang.org/x/term"
 )
 
 const statuslineWidthOffset = 7
@@ -197,11 +197,11 @@ func getGitInfo(cwd string) string {
 }
 
 func getTerminalWidth() int {
-	ws, err := unix.IoctlGetWinsize(int(os.Stdout.Fd()), unix.TIOCGWINSZ)
+	width, _, err := term.GetSize(int(os.Stdout.Fd()))
 	if err != nil {
 		return 80
 	}
-	return int(ws.Col)
+	return width
 }
 
 var ansiRegex = regexp.MustCompile(`\x1b\[[0-9;]*m`)