* fix: address 18 bugs found during codebase audit
High severity:
- TPE/MOTPE: match parameters by exact distribution equality instead of
flat-mapping over all param values, preventing cross-parameter mixing
- MultivariateTpeSampler: find_matching_param now uses search space
distributions for exact matching instead of type+range heuristic
- JournalStorage: write_to_file no longer advances file_offset (left to
refresh), both operations serialized under single io_lock mutex,
refresh uses fetch_max and deduplicates by trial ID
Medium severity:
- NSGA-III: use actual Pareto front ranks for tournament selection
instead of artificial cyclic indices
- sample_random: apply step quantization after log-scale sampling
- internal_bounds: return None for non-positive log-scale bounds
- SobolSampler: use per-trial dimension HashMap for concurrent safety
- JournalStorage refresh: protect with io_lock mutex, use fetch_max
- n_trials(): filter by TrialState::Complete as documented
- FloatParam: reject NaN/Infinity in validate()
- Pruners: assert n_min_trials >= 1, guard compute_percentile on empty
- Visualization: escape_js for importance chart parameter names
Low severity:
- save(): use peek_next_trial_id() from Storage trait
- csv_escape: handle carriage return per RFC 4180
- from_internal: use saturating arithmetic for stepped Int distributions
- BoolParam: bounds-check categorical index < 2
- min_max: skip NaN values with safe fallback
* ci: trigger CI on pull requests targeting any branch
- Add sampler/common.rs with distribution helpers (internal_bounds,
from_internal, to_internal, sample_random) used by 8 samplers
- Add sampler/tpe/common.rs with TPE sampling functions
(sample_tpe_float, sample_tpe_int, sample_tpe_categorical)
shared by TpeSampler, MultivariateTpeSampler, and MotpeSampler
- Remove ~940 lines of near-identical code across sampler modules
Manuel