Isolate explicit S/R gate target ladder

reports/README.md

@@ -46,3 +46,11 @@ 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.
+
+The explicit gate-ladder parity run writes:
+
+- `backtest-sr-full-explicit_target_ladder.json`
+- `sr-explicit-target-ladder-comparison.json`
+- `sr-explicit-target-ladder-cohorts.csv`
+
+Retain these only if they establish the final parity decision.