refactor(net): converge live session state reset

src/AcDream.Core/Combat/CombatState.cs

@@ -178,6 +178,21 @@ public sealed class CombatState
     public void Clear()
     {
         _healthByGuid.Clear();
-        SetCombatMode(CombatMode.NonCombat);
+        CurrentMode = CombatMode.NonCombat;
+
+        Action<CombatMode>? listeners = CombatModeChanged;
+        if (listeners is null)
+            return;
+
+        List<Exception>? failures = null;
+        foreach (Action<CombatMode> listener in listeners.GetInvocationList())
+        {
+            try { listener(CombatMode.NonCombat); }
+            catch (Exception error) { (failures ??= []).Add(error); }
+        }
+        if (failures is not null)
+            throw new AggregateException(
+                "One or more combat reset observers failed.",
+                failures);
     }
 }