updated main menu for cooperate mode

src/states/MenuState.h

@@ -107,4 +107,8 @@ private:
     int coopSetupSelected = 0; // 0 = 2 players, 1 = AI
     SDL_FRect coopSetupBtnRects[2]{};
     bool coopSetupRectsValid = false;
+    // Optional cooperative info image shown when coop setup panel is active
+    SDL_Texture* coopInfoTexture = nullptr;
+    int coopInfoTexW = 0;
+    int coopInfoTexH = 0;
 };