{# One request per keystroke parks the draft - so that a trip to the filter and back
keeps it - and answers with the preview, which is why the response is swapped into
the pane instead of being thrown away. hx-trigger replaces htmx' default submit
trigger, the "Vorschau an mich senden" button still posts natively.
Deliberately without htmx' "changed" modifier: it compares the listening element's
.value between events, and a