- Corrected success gate logic to `> 0`.
- Added INFO logging for all attempted ICP pairs.
- Ensured all pairs are stored in `metrics.per_pair_results`.
- Fixed overlap skip logging to use DEBUG level.
- Fixed syntax and indentation errors in `aruco/icp_registration.py` that were causing unreachable code and malformed control flow.
- Relaxed success gate to `metrics.num_cameras_optimized > 0`, allowing single-camera optimizations to be considered successful.
- Implemented comprehensive per-pair diagnostic logging: INFO for ICP results (fitness, RMSE, convergence) and DEBUG for overlap skips.
- Ensured all attempted ICP results are stored in `metrics.per_pair_results` for better downstream diagnostics.
- Updated `tests/test_icp_registration.py` to reflect the new success gate logic.

## Task 3: 3D AABB Overlap Check
- Implemented `compute_overlap_3d` in `aruco/icp_registration.py`.
- Added `overlap_mode` to `ICPConfig` (defaulting to "xz").
- Verified 3D overlap logic with new tests in `tests/test_icp_registration.py`.
- Confirmed that empty inputs return 0.0 volume.
- Confirmed that disjoint boxes return 0.0 volume.
- Confirmed that partial and full overlaps return correct hand-calculable volumes.

## Task 2: Point Extraction & Preprocessing
- Implemented `extract_scene_points` with floor, hybrid, and full modes.
- Implemented `preprocess_point_cloud` with statistical outlier removal (SOR).
- Added `region` field to `ICPConfig` dataclass.
- Added comprehensive tests for new extraction modes and preprocessing.
- Verified backward compatibility for floor mode.
- Verified hybrid mode behavior (vertical structure inclusion and fallback).
- Verified full mode behavior.
- Verified SOR preprocessing effectiveness.