fix(auth): address Task 13 deployment review findings

tools/tht/internal/backup/restore_disk_windows.go

@@ -0,0 +1,21 @@
+//go:build windows
+
+package backup
+
+import (
+	"errors"
+
+	"golang.org/x/sys/windows"
+)
+
+func restoreFreeBytes(target string) (uint64, error) {
+	path, err := windows.UTF16PtrFromString(target)
+	if err != nil {
+		return 0, errors.New("restore filesystem capacity is unavailable")
+	}
+	var available uint64
+	if err := windows.GetDiskFreeSpaceEx(path, &available, nil, nil); err != nil {
+		return 0, errors.New("restore filesystem capacity is unavailable")
+	}
+	return available, nil
+}