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.

frontend/src/components/charts/horizon.tsx

@@ -39,7 +39,7 @@ export function RBar({ r, max = 1.6 }: { r: number | null; max?: number }) {
 }
 
 /* ------------------------------------------------------------------ */
-/* PriceRail — stop → entry → now → target laid out spatially           */
+/* PriceRail — stop → entry → now → gate level laid out spatially       */
 /* ------------------------------------------------------------------ */
 
 export function PriceRail({
@@ -69,7 +69,7 @@ export function PriceRail({
   const progressWidth = current != null ? Math.abs(pct(current) - pct(entry)) : 0;
   return (
     <div className="hz-rail" role="img" aria-label={
-      `Stop ${fmt(stop)}, entry ${fmt(entry)}, now ${current != null ? fmt(current) : 'unknown'}, target ${fmt(target)}`
+      `Stop ${fmt(stop)}, entry ${fmt(entry)}, now ${current != null ? fmt(current) : 'unknown'}, gate ${fmt(target)}`
     }>
       <div className="hz-rail-track" />
       <div
@@ -111,10 +111,10 @@ export function PriceRail({
           </span>
         </div>
       )}
-      <div className="hz-rail-mark" style={{ left: `${pct(target)}%` }}>
+      <div className="hz-rail-mark" style={{ left: `${pct(target)}%` }} title="Gate level — screening only, not a take-profit">
         <span className="hz-rail-ring" />
         <span className="hz-rail-label">
-          <em>target</em>
+          <em>gate</em>
           <b>{fmt(target)}</b>
           {rTarget != null && <i>+{fmt(rTarget, 1)}R</i>}
         </span>