- load_scree_data: return [] with TODO until schema stores EVR metadata
- load_party_axis_scores: compute from vectors instead of missing table
- load_party_axis_scores_for_window: same vector-based fallback
- load_party_scores_all_windows[_aligned]: check table existence,
fall back to computing from load_positions when absent
All functions predated decomposition (5afbad1, 2026-04-05) and relied on
party_axis_scores / sv_metadata columns that were never created.