fix: harden thothctl Windows safe I/O

tools/thothctl/internal/testsupport/symlink.go

@@ -0,0 +1,19 @@
+// Package testsupport provides portable helpers shared by thothctl tests.
+package testsupport
+
+import (
+	"os"
+	"testing"
+)
+
+// SymlinkOrSkip creates a symlink or skips only when Windows reports that symlink privilege is
+// unavailable. All other failures remain test failures.
+func SymlinkOrSkip(t testing.TB, target, link string) {
+	t.Helper()
+	if err := os.Symlink(target, link); err != nil {
+		if isSymlinkPrivilegeUnavailable(err) {
+			t.Skip("Windows symlink privilege is unavailable")
+		}
+		t.Fatal(err)
+	}
+}