BUGFIX: Fix skillMaxUpgradeCount returning 1 at extreme skill levels (#2611)

src/Bladeburner/Skill.ts

@@ -81,6 +81,9 @@ export class Skill {
   }
 
   calculateMaxUpgradeCount(currentLevel: number, cost: PositiveNumber): number {
+    // At extreme levels, floating-point precision loss makes currentLevel + 1 === currentLevel,
+    // causing calculateCost to return 0. No upgrade is possible in this case.
+    if (this.calculateCost(currentLevel, 1 as PositiveInteger) <= 0) return 0;
     /**
      * Define:
      * - x = count