fix: align production defaults and close review parity gaps

Ship greenfield min_rr=2.0 and conf=0, read-only Structural S/R, indicator
cache invalidation, and UI/gate language that treats GTL as screening not exit.
Align strategy_rank missing-vol fallback live vs backtest, single-source
PRIMARY_TARGET_MIN_RR, expand prod parity tests, and drop dead FE clients.

app/services/admin_service.py

@@ -54,7 +54,9 @@ _ACTIVATION_BOOL_KEYS: dict[str, str] = {
 }
 ACTIVATION_DEFAULTS: dict[str, float | bool] = {
     "min_momentum_percentile": 80.0,
-    "min_rr": 1.2,
+    # Production floor from the 2026-07-12 min_rr sweep (in-sample and OOS peak).
+    # 1.2 was the old code default and the trough next to the spike — do not restore.
+    "min_rr": 2.0,
     # 0 = off. The July 2026 gate ablation showed the confidence floor added
     # nothing (identical net/trade with it removed, under both exit models)
     # while cutting ~25% of qualified trades.