Mechanical sweep: prefer plain 'as X' over 'as unknown as X' where the compiler allows it

What

A sweep of the corpus's 97 as unknown as sites found several documented-legitimate casts
(real @types/three gaps: PassNode.options — B11, BloomNode.highPassFn — B24,
Points.count — B34) that typecheck fine with the unknown intermediate hop dropped — a
plain as { options: … } / as ReturnType<typeof …> compiles clean, because the target
type still overlaps the source closely enough for TS's single-step assertion rule.

The double-hop form isn't wrong (it's the maximally-permissive form and never fails), but
it's stronger than the gap requires and reads as "TS is fighting me here" when a lighter
cast would do. One family (the backgroundNode/fogNode/environmentNode sites) was
already fully removed in an earlier sweep because @types/three closed that gap entirely.
This issue is about the remaining ~10 files' worth of double-hop casts that are still
necessary but could be single-hop.

Why it matters

Corpus-wide in reach but cosmetic — no correctness or behavior change, purely how tightly
each cast is scoped. Worth doing as a deliberate, verifiable pass (test each site with
as X, keep as unknown as X only where the compiler still demands it) rather than
mixed into an unrelated task, since verifying ~10 sites individually against tsc is
exactly mechanical-but-not-zero-risk enough to want its own PR and diff.

Recommendation already on file

docs/REVIEW-QUEUE.md #16: worth doing in the same pass as whatever normalizes the B11
comment wording, not as a rushed follow-up to a task whose ask was "remove the unnecessary
ones" rather than "minimize the necessary ones."

Pointer

docs/REVIEW-QUEUE.md §16 ("as unknown as X vs plain as X — should the corpus prefer
the minimal cast?").

Read docs/REVIEW-QUEUE.md §16, then search the corpus for the remaining as unknown as sites, especially the documented B11, B24, and B34 cases. Try the corresponding single-step assertions and verify each with tsc; done means eligible casts use the plain form while casts still required by the compiler remain unchanged.