The container's `Pard` is now the only decoder of parameter definitions:
`EffectParam` delegates to it and the export's test reference reads its
encoded table back through it (no big-endian readers of its own). The
export stores a checkbox default as on/off, as the importer reads it.
Inside a strongly connected component of candidate precomp links (a file
with a precomp loop), the per-composition searches share one budget of
link visits; past it, a layer that would need a search is refused and
reported, which never lets a loop in. Below the budget the decisions are
the old ones exactly.