fix(go/fio): accept 2-digit year format in transparent date parser

Fio's transparent account page now serves dates as DD.MM.YY (e.g.
07.05.26) rather than the previously expected 4-digit-year format.
Extends parseCzechDate to try all eight layout variants: padded and
non-padded, dot and slash separators, 4-digit and 2-digit years.

Go maps 2-digit year 00-68 → 2000-2068, so 26 → 2026.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

go/internal/io/fio/transparent.go

@@ -209,7 +209,10 @@ func hasClass(t ghtml.Token, cls string) bool {
 // Returns "" on parse error.
 func parseCzechDate(s string) string {
 	s = strings.TrimSpace(s)
-	for _, layout := range []string{"2.1.2006", "02.01.2006", "2/1/2006", "02/01/2006"} {
+	for _, layout := range []string{
+		"2.1.2006", "02.01.2006", "2/1/2006", "02/01/2006",
+		"2.1.06", "02.01.06", "2/1/06", "02/01/06",
+	} {
 		if t, err := time.Parse(layout, s); err == nil {
 			return t.Format("2006-01-02")
 		}