Simplify dead HP preservation to explicit zero (#665)

Stat rebuild via AddBase/AddTotal restores Current to Total, but a dead
player must stay at 0 HP until revived. Set HP explicitly to 0 instead
of preserving the previous value.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: AngeloTadeucci

Maple2.Server.Game/Manager/StatsManager.cs

@@ -140,6 +140,13 @@ public void Refresh() {
         AddBuffs(player);
         Values.Total();
         StatConversion(player);
+
+        // Stat rebuild via AddBase/AddTotal restores Current to Total,
+        // but a dead player must stay at 0 HP until revived.
+        if (player.IsDead) {
+            Values[BasicAttribute.Health].Current = 0;
+        }
+
         Actor.Field.Broadcast(StatsPacket.Init(player));
         Actor.Field.Broadcast(StatsPacket.Update(player), player.Session);