Test clean S/R as production rank overlay

reports/README.md

@@ -41,3 +41,8 @@ The full-period production comparison writes:
 
 Those outputs should be retained as the final decision point for this research
 branch.
+
+The follow-up breadth-preserving ranking experiment writes
+`backtest-sr-overlay-full.json`. Retain it only as the decision point for the
+pre-registered 5% clean-structure overlay; exploratory weight sweeps should not
+be committed.