- compute_svd_for_window now computes explained variance ratio (s²/sum(s²))
and appends it as a metadata row (entity_type='metadata',
entity_id='explained_variance') to motion_rows
- load_scree_data reads this metadata row from svd_vectors instead of
querying the non-existent sv_metadata column
- run_svd_for_window counts only entity_type='motion' rows in stored_motion
so metadata rows don't inflate the count
- Added 5 TDD tests covering load, compute, store, and round-trip
All 227 tests pass.
sgeboers
6e36fa2604