- Correct phase difference methods to compute actual input-output phase
  difference instead of absolute output phase (critical bug fix)
- Remove dead code, commented-out blocks, and passthrough wrappers
- Add user_choice_frequency() to UserInteraction for consistent UI
- Move dB conversion logic from main.py to process.format_poi_values()
- Derive POI_LABELS from process.POIS to keep a single source of truth
- Separate compute_all_pois() from data persistence (save handled by caller)
- Update README to reflect current HDF5-based architecture

Made-with: Cursor