One node, edited in parts: a date as three selects

A single YYYY-MM-DD string on one node is edited by a nested Fore. The fx-control hands its node to the sub-Fore with initial="." and src; the sub-Fore (date-parts/date.html) splits the value into a scratch instance, edits year, month and day in separate selects and returns the joined value with fx-return. Its labels come from the outer Fore's shared lang instance, so they follow the language switch.