refactor(cli): rename operator command to tht

tools/tht/internal/safeio/linkcount_unix.go

@@ -0,0 +1,13 @@
+//go:build !windows
+
+package safeio
+
+import (
+	"os"
+	"syscall"
+)
+
+func hasSingleLink(info os.FileInfo) bool {
+	stat, ok := info.Sys().(*syscall.Stat_t)
+	return ok && stat.Nlink == 1
+}