fix(ui): commit date-picker selections immediately instead of on confirm (#6122)

* fix(ui): commit date-picker selections immediately instead of on confirm

With showTime, Ant Design's DatePicker stages a clicked date until the
OK button confirms it. Closing the dropdown any other way - clicking
elsewhere in the form or hitting Create/Save directly - discarded the
staged date without a hint, so an inbound saved this way ended up with
expiryTime=0 (never expires). The Now shortcut commits in one click,
which made it look like only the current time could ever be set.

Drop the confirm step (needConfirm=false) and propagate every calendar
selection through onCalendarChange, so the picked date reaches the form
state the moment it is clicked and can no longer be lost to a race with
the submit button.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* test(ui): pin calendar clicks committing without a confirm press

A clicked day cell must reach onChange with the exact selected
timestamp while the dropdown is still open, and the footer must not
render a confirm button. Pins the needConfirm-free behavior so a picker
dependency bump cannot silently bring the staged-value discard back.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/form/DateTimePicker.tsx

@@ -121,7 +121,9 @@ export default function DateTimePicker({
     <DatePicker
       value={value}
       onChange={(next) => onChange(next || null)}
+      onCalendarChange={(next) => onChange((Array.isArray(next) ? next[0] : next) || null)}
       showTime={showTime ? { format: 'HH:mm:ss' } : false}
+      needConfirm={false}
       format={format}
       placeholder={placeholder}
       disabled={disabled}