fix(fail2ban): sort banned IPs by timestamp via orthogonal data

Previous code wrapped the formatted DD.MM.YYYY HH:MM string in
<span data-order="${timestamp}">, expecting DataTables to read the
attribute for sort. DataTables only inspects data-order on the <td>
itself, so the attribute was ignored and the visible string was
sorted lexicographically (05.05.2026 landed before 30.04.2026).

Switch the "Ban date" and "Expires" columns to DataTables orthogonal
data: store the raw unix timestamp in the row, format only when
type === 'display'. Missing timestamps pushed as null so they sort
to the end on ascending order. Guard the display branch with
Number.isFinite(data) && data > 0 to keep stray Infinity/NaN from
producing "NaN.NaN.NaN NaN:NaN".

Author: boffart