LLVM-oriented PRNG helpers shared with genetic algorithms and Monte Carlo.
Prefer these over ``Random.ae`` inside ``@llvm`` / ``@gpu`` bodies: they are
pure ``Int`` steps with no Python ``random`` object. Call sites that need a
compiled kernel should re-export or wrap them under ``@llvm`` / ``@gpu``
(see ``examples/knapsack_ga.ae`` for a functional GA; use these helpers inside
``@llvm`` / ``@gpu`` kernels when you need a compiled PRNG).