docs: update README and finalize ground plane refinement integration

py_workspace/.sisyphus/notepads/ground-plane-refinement/learnings.md

@@ -5,3 +5,28 @@
 - Verified imports:
   - open3d: 0.19.0
   - h5py: 3.15.1
+
+## [2026-02-09] Ground Plane Detection Implementation
+- Implemented `unproject_depth_to_points` using vectorized NumPy operations for efficiency.
+- Implemented `detect_floor_plane` using Open3D's `segment_plane` (RANSAC) with deterministic seeding.
+- Implemented `compute_consensus_plane` with weighted averaging and normal alignment to handle flipped normals.
+- Implemented `compute_floor_correction` using `rotation_align_vectors` for minimal rotation (preserving yaw) and vertical translation.
+- Added comprehensive tests covering edge cases (outliers, bounds, identity transforms).
+- Refactored to use `FloorPlane` and `FloorCorrection` dataclasses for structured outputs.
+- Fixed test logic for `compute_consensus_plane` to correctly account for normal normalization effects on `d`.
+- Verified type safety with `basedpyright` (0 errors, only expected warnings).
+
+## [2026-02-09] Ground Plane Diagnostic Visualization
+- Implemented `create_ground_diagnostic_plot` using Plotly `go.Figure`.
+- Visualization includes:
+  - World origin axes (RGB triad).
+  - Consensus plane surface (semi-transparent gray).
+  - Per-camera floor points (scatter3d).
+  - Camera positions before (red) and after (green) refinement.
+- Added `save_diagnostic_plot` for HTML export.
+- Verified with smoke tests in `tests/test_ground_plane.py`.
+
+## [2026-02-09] Final Integration
+- Full test suite (90 tests) passed successfully.
+- basedpyright verified on new modules (depth_save.py, ground_plane.py, refine_ground_plane.py).
+- README updated with Ground Plane Refinement workflow.