syncIdentity unconditionally recomputed mon.shiny from the mon's DVs,
overwriting whatever was there. It is wired into refreshStats, which
SummaryMenu.new calls on every menu open, so a forced shiny -- Mon.new's
opts.shiny path, DVs that do not themselves read as shiny -- got
un-shinied the moment the summary screen opened, even though opts.shiny
already wins over shiny.roll at construction for exactly this case (a
scripted shiny is the cart overriding the roll, not a roll to be
hooked).
mon.shiny now only ever gets PROMOTED by the DV check, never demoted:
`mon.shiny or Mon.isShiny(...)`. A naturally shiny mon and a plain one
are unaffected -- the DV check still runs and still decides the first
time -- and a mon whose DVs are edited to justify shininess later still
promotes normally; only an already-true shiny stops being able to flip
back to false on a later refresh.