feat: arbre d'évolution 3 voies — ponte/marais/adaptation

18 nœuds (6/branche), nœuds exclusifs (pick one), reset gratuit.
Nouveaux effets : double_click, auto_click, crit, generator_boost,
cost_reduction, prestige_dna_bonus, offline_boost, threshold_reduction.
UI 3 colonnes colorées, seuil prestige dynamique, coût réduit.
75 tests (tous passent).

Frontend/src/store/useGameStore.ts

@@ -10,6 +10,7 @@ import {
   applyClick,
   buyGenerator,
   buyEvolutionNode,
+  resetEvolutionTree,
   applyPrestige,
   canPrestige as canPrestigeCheck,
   totalProductionPerSecond,
@@ -65,10 +66,12 @@ interface GameStore {
   buy: (genId: string) => void;
   buyNode: (nodeId: string) => void;
   prestige: () => void;
+  resetTree: () => void;
   reset: () => void;
   loadFromServer: (serverState: GameState) => void;
   initGuest: () => void;
   generatorCost: typeof genCost;
+  generatorCostWithTree: (gen: Parameters<typeof genCost>[0]) => number;
 }
 
 function hydrateWithOffline(saved: GameState, now: number): { state: GameState; report: OfflineReport | null } {
@@ -194,6 +197,18 @@ export const useGameStore = create<GameStore>((set, get) => ({
     });
   },
 
+  resetTree: () => {
+    if (!get().ready) return;
+    set((s) => {
+      const updated = resetEvolutionTree(s.state);
+      saveLocal(updated);
+      return {
+        state: updated,
+        productionPerSecond: totalProductionPerSecond(updated),
+      };
+    });
+  },
+
   reset: () => {
     const fresh = { ...DEFAULT_STATE, lastTick: Date.now(), lastOnline: Date.now() };
     saveLocal(fresh);
@@ -233,4 +248,5 @@ export const useGameStore = create<GameStore>((set, get) => ({
   },
 
   generatorCost: genCost,
+  generatorCostWithTree: (gen) => genCost(gen, get().state.evolutionTree),
 }));