ADR 0005: Remove legacy MAP-Elites embedding flows

Date: 2026-01-06

Context: MAP-Elites uses repo-state embeddings; additional embedding flows increase complexity and schema surface without improving the active pipeline. Decision: Keep a single repo-state embedding pipeline and remove summary embeddings, changed-files preprocessing, and MAPELITES_EMBEDDING_MODE. Details: PCA history stores only (commit_hash, vector, embedding_model) via PcaHistoryEntry and map_elites_pca_history.embedding_model. Details: Snapshot persistence keeps metadata in map_elites_states.snapshot, occupied cells in map_elites_archive_cells, and PCA history rows in map_elites_pca_history. Constraints: Loreley does not ship migrations; schema changes are applied via uv run loreley reset-db --yes. Consequences: MAPELITES_SUMMARY_* settings and changed-files preprocessing APIs are removed; deployments must reset DB to upgrade.