Fix FoW compile errors

Author: Belzedar94

src/imperfect/Expander.cpp

@@ -202,7 +202,7 @@ void Expander::expand_leaf(GameTreeNode* leaf, Subgame& subgame, Position& pos)
     infoset->variances.resize(numActions, 2.0f); // Variance prior {-1, +1}
 
     // Initialize to best child (Appendix B.3.4)
-    initialize_to_best_child(infoset, childEvals);
+    initialize_to_best_child(infoset.get(), childEvals);
 
     infoset->expanded = true;
 }

src/imperfect/Subgame.cpp

@@ -280,6 +280,7 @@ void Subgame::mark_frozen_state(GameTreeNode* node) {
 float compute_alternative_value(const InfosetNode* infoset,
                                  const std::vector<float>& currentX,
                                  const std::vector<float>& currentY) {
+    (void)currentX; // Suppress unused parameter warning
     if (!infoset)
         return 0.0f;