Reduce parser state to syntax array (monad)

[bpstrngr]

depth, action, etc transient states can be stored on last element of the monad. (at https://github.com/bpstrngr/interface/blob/fragments/Blik_2023_fragment.js#L317 and in meta.js

• once they settle, they can be merged by taking the semiotic operators as secondary argument)

prerequisite to #4