1f83233d

By: ValentinHirschi <valentin.hirschi@gmail.com>

specialize sampling Jacobians and isolate worker buffers

Compile only the three active joint Jacobian columns, and use a scalar eager
program for inverse reconstruction. Validate exact column contracts at map
binding. Clone nested mutable evaluator buffers through the existing dyn-clone
facility instead of sharing the outer embedded composition across workers.

Fix a separately reproduced CT-disabled crash by preparing deferred overlap
samples only when subtraction is enabled. Retain the old optimized GL638
rotation diagnostic: canonical sampling is unchanged, while Euler and exact-z
physical probes differ; actual GL638 diagnosis and the cost gate remain open.

Validation: 137 focused/generated core tests, including full8192 hosted and
all18-orientation amplitude acceptance; all-target core/API check and clippy
(no changed-line diagnostics); optimized CLI build; archive hashes verified.
The separately optimized scalar primal may differ by one Arb ulp; its new
comparison uses a native-roundoff bound. Active3/full17 Jacobians still compare
exactly, and physical/normalization tolerances are unchanged.
Runtime caches remain transient; no saved-state format migration.

User request:
(continue as planned but make sure the time spent in the sampling maps is still quite significantly less than the actual GL638 all-orientation integrand, i.e. it's not crucial to optimize the runtime of the sampling, except if it is somehow comparable to the integrand time; it should be like 10% at the very most, once below that then no need to optimize further).

Timeline