wip close round/campaign/war + refacto json None

src/warchron/model/round.py

@@ -104,6 +104,11 @@ class Round:
             for bat in self.battles.values()
         )
 
+    def all_battles_finished(self) -> bool:
+        return all(
+            b.winner_id is not None or b.is_draw() for b in self.battles.values()
+        )
+
     def create_battle(self, sector_id: str) -> Battle:
         if sector_id not in self.battles:
             battle = Battle(sector_id=sector_id, player_1_id=None, player_2_id=None)