[DEBUG] FEXT CI failure investigation

[nicole-graus]

Throwaway draft to reproduce and diagnose the CI-only test_prove_elfs_fext FEXT_PAGE composition failure (passes locally on arm64/Rosetta-x86, fails on CI x86-64 Linux). This commit dumps the FEXT_PAGE trace and checks its constraints so the CI failure log shows whether the honest trace violates a constraint (trace/UB) or is clean (composition-computation bug). Not for merge.

[github-actions]

Benchmark Results for modified programs 🚀

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
head ecsm	2.7 ± 0.1	2.6	2.8	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
head hashmap	105.7 ± 3.6	100.4	111.4	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
head keccak	102.5 ± 2.2	99.0	105.2	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
head syscall_commit	75.4 ± 0.8	74.5	76.6	1.00

[github-actions]

Benchmark Results for unmodified programs 🚀

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base binary_search	38.1 ± 1.2	36.7	40.0	1.00 ± 0.03
head binary_search	38.0 ± 0.6	36.5	38.7	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base bitwise_ops	36.9 ± 1.1	35.1	38.8	1.00
head bitwise_ops	39.1 ± 4.1	35.2	47.2	1.06 ± 0.12

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base fibonacci_26	39.4 ± 0.9	38.0	40.8	1.00
head fibonacci_26	40.1 ± 0.8	38.6	41.1	1.02 ± 0.03

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base matrix_multiply	37.7 ± 1.3	36.4	39.8	1.00
head matrix_multiply	38.6 ± 1.0	37.3	40.3	1.02 ± 0.04

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base modular_exp	36.8 ± 1.1	35.2	38.9	1.00
head modular_exp	37.4 ± 0.9	36.1	38.8	1.02 ± 0.04

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base quicksort	40.9 ± 1.2	39.2	43.1	1.05 ± 0.03
head quicksort	39.1 ± 0.5	38.3	39.7	1.00

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base sieve	40.4 ± 0.9	38.9	42.0	1.00
head sieve	40.5 ± 1.0	39.1	42.3	1.00 ± 0.03

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
base sum_array	47.0 ± 1.3	45.2	49.1	1.00
head sum_array	48.6 ± 1.9	46.8	53.0	1.03 ± 0.05