- Move all _factor_* methods from pathfinder.py to path.py
- Add get_candidates() and compute_weights() to Path class
- Simplify step() to just commit chosen candidate
- Add normalized_scores field for consistent influence calculation
- Remove duplicate transposition/voice_map logic between get_candidates and step
- dca_voice_movement and target_range now use destination_chord directly
- Remove Candidate class, use PathStep for both hypothetical and actual steps
- Simplify Path.step() to accept a PathStep
- Fix DCA Hamiltonian to return visit_count directly instead of normalized score
- Tests pass and DCA properly discriminates