Previously two formats showed up next to each other: raw ISO
(YYYY-MM-DD) where DB values were interpolated directly, and
toLocaleDateString('de-DE') output (D.M.YYYY without leading
zeros) where formatDate was used.
- formatDate / formatDateTime now build the string explicitly with
zero-padded day and month, so dates render as DD.MM.YYYY (and
DD.MM.YYYY HH:MM for timestamps) regardless of locale.
- Replaced the remaining raw uses (Anbieter-Admin createdAt,
Mitarbeiter-Prozentsätze gueltig_ab, the new Benutzer tab's
createdAt, PDF export date filters and footer).
- Native <input type=\"date\"> fields are unchanged — they require
the ISO value internally and render localized in the picker.