refactor: simplify Value benchmarks with Cardano-compliant constraints

Refactor the Value benchmarking suite to use Cardano-compliant key sizes
(32-byte max) and leverage the new Logarithmic wrapper for accurate
modeling of logarithmic operations.

Key changes:
- Apply Logarithmic wrapper to lookupCoin and valueContains benchmarks
  for proper O(log n) cost modeling
- Consolidate key generators from 4 functions to 2, eliminating duplication
- Remove obsolete key size parameters throughout (keys always maxKeyLen)
- Extract withSearchKeys pattern to eliminate repetitive code
- Simplify test generation by removing arbitrary key size variations
- Clean up lookupCoinArgs structure for better readability

The refactoring reduces the module from 359 to 298 lines while improving
clarity and ensuring all generated Values comply with Cardano's 32-byte
key length limit.

Author: Unisay