fix: particule clic affiche le vrai gain (clickMult × prestigeMult × treeMult)

Ajout getClickGain() dans economy.ts — utilisé par la particule de feedback
et le cockpit header "Ponte". Avant : affichait toujours +1.

Frontend/src/components/CockpitHeader.tsx

@@ -2,11 +2,13 @@
 
 import { useGameStore } from "../store/useGameStore";
 import { formatNumber } from "../utils/formatNumber";
+import { getClickGain } from "../core/economy";
 
 export function CockpitHeader() {
   const productionPerSecond = useGameStore((s) => s.productionPerSecond);
-  const { clickMultiplier, prestigeMultiplier, ancestralDna, prestigeCount } =
-    useGameStore((s) => s.state);
+  const state = useGameStore((s) => s.state);
+  const { prestigeMultiplier, ancestralDna, prestigeCount } = state;
+  const clickGain = getClickGain(state);
 
   return (
     <div className="gp gp-cockpit-header">
@@ -18,7 +20,7 @@ export function CockpitHeader() {
       </div>
       <div className="gp-stat">
         <span className="gp-label">Ponte</span>
-        <span className="gp-value">x{clickMultiplier}</span>
+        <span className="gp-value">{formatNumber(clickGain)}</span>
       </div>
       <div className="gp-stat">
         <span className="gp-label">Mult</span>