43b10f91c0
From dev testing: - BillEditor 'Geplanter Versand' was a native <input type=datetime-local> → rendered US date + 12h regardless of settings. Split into LocalizedDateInput + TimeField (honour general_date_format + general_time_format), recombined into the YYYY-MM-DDTHH:MM the payload/scheduler expect. - InstallmentsPanel 'Send on' native <input type=date> (browser-locale via a lang hint, wrong in Safari/Firefox) → LocalizedDateInput, consistent in every browser. (Luca approved converting it.) - Business-profile Timezone was a free-text input → dropdown of the full IANA list (Intl.supportedValuesOf, CH/LI fallback), blank = system default.