Avoid redundant native layout, hidden hit testing and scroll replay

[wintergraham]

Animated native pages repeatedly measured equivalent layout constraints, replayed consumed scroll copies, and hit-tested retained hidden page trees. This change reuses valid geometry and intrinsic probes, prunes hidden/clipped input subtrees, and consumes each scroll flush once per renderer. Paint-only clip changes avoid layout invalidation.

CPU stage totals now survive trace-ring eviction, and the GPU query pool accommodates the motion lab without dropping nearly every sample.

Validation:

• Lumine core: 358 passed, 2 ignored.
• GPU scroll replay regression: real pixel readback passed.
• Native host integration: 163 passed; the same 6 failures reproduce at the supplied Ask baseline.
• Whole-lab CPU/GPU profiling uses Linux llvmpipe; hardware Metal performance remains unmeasured.

Based on the requested 390a7f4 history. Companion Ask branch: wintergraham/ask:codex/profile-native-motion.