Support for ending battles when only one side has creatures that are available for battle.

src/Battling/Models/Battle.cpp

@@ -97,3 +97,20 @@ bool Battle::CanSlotBeFilled(uint8_t side, uint8_t index) const {
     }
     return false;
 }
+
+void Battle::ValidateBattleState() {
+    bool survivingSideExists = false;
+    uint8_t result = 0;
+    for (uint8_t i = 0; i < _sides.size(); i++){
+        auto side = _sides[i];
+        if (!side->IsDefeated()){
+            if (survivingSideExists){
+                return;
+            }
+            survivingSideExists = true;
+            result = i;
+        }
+    }
+    this->_battleResult = result;
+    this->_hasEnded = true;
+}