- Replace Mutex<fastrand::Rng> with a stored seed + MurmurHash3 mixer
in RandomSampler, TpeSampler, and MotpeSampler so parallel workers
no longer serialize on a shared lock
- Add mix_seed() and distribution_fingerprint() to rng_util for
deterministic per-call RNG derivation from (seed, trial_id, distribution)
- Include an AtomicU64 call counter to disambiguate parameters that
share the same distribution within a trial
fastrand is smaller, faster, and has no dependencies. Add rng_util
helper for f64 range generation since fastrand lacks a built-in
equivalent. Migrate all samplers, KDE modules, and fANOVA to use
fastrand's concrete Rng type instead of rand's trait-based generics.
Manuel Raimann