fix: harden thothctl Windows safe I/O

tools/thothctl/internal/testsupport/symlink_test.go

@@ -0,0 +1,12 @@
+package testsupport
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestSymlinkPrivilegeUnavailableDoesNotMatchUnrelatedErrors(t *testing.T) {
+	if isSymlinkPrivilegeUnavailable(errors.New("unrelated symlink failure")) {
+		t.Fatal("unrelated symlink failure was classified as a missing Windows privilege")
+	}
+}