feat: address problematic benchmark tests

[DavePearce]

Note

Standardizes boolean/casting and constraint logic across OOB/MODEXP benches, updates bit shift asm helpers, and widens/enables test coverage (incl. lookup suites and fields).

• Bench/Constraint Logic (Lisp):
  • Normalize boolean handling via i1 casts and use of ==/!= in multiple modules (testdata/corset/bench/oob.lisp, mul.lisp, mod.lisp, stp.lisp).
  • Refactor predicates and hub-prediction justifications (e.g., ECPAIRING, MODEXP_*, CALL/CREATE, BLAKE2F) and inline certain DIV calls for constant components.
  • Add helper prc-modexp-pricing---f-of-max-elog; adjust various *_is_zero/flag accessors to i1.
• ASM Utilities:
  • Update bit-shift implementations: revise bit_sar256_u1 and bit_shr256_u1 decompositions and workarounds in testdata/asm/util/bit_sar.zkasm and bit_shr.zkasm.
• Tests:
  • Enable/restore agnostic lookup tests lookup_04..07 and include .bls12_377.rejects datasets; prune/comment large-case rejects in generic files.
  • Expand field coverage across many assembly unit/util tests (notably adding field.KOALABEAR_16 and field.GF_8209), add Test_AsmUtil_BitSar.
  • Adjust some assembly bench tests to run only on field.BLS12_377 with issue references; include KOALABEAR_16 for corset/bench/oob.
  • Add GF_8209 to corset/valid/lookup_03.

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