fix: CheckWin缺少wildcard/258参数导致武汉麻将0%胡牌 + 庄家第一轮跳过摸牌

Root cause 1: 所有CheckWin调用未传wildcardCount/require258Pair
- StepTurn自摸: 5处遗漏 → 癞子在手牌中被当废牌
- HandleDiscardReactions: 2处遗漏
- PhaseMachine: 2处遗漏
→ 武汉麻将永远不能胡牌

Root cause 2: 庄家开局14张+摸牌=15张, CheckWin守卫≠14拒绝
→ 庄家永远不能自摸 → 修复: 庄家第一轮跳过摸牌

额外修复:
- RandomMahjongAI: 永远不出癞子(预留wildcard)
- ScoreEngine.FanValue: 从DSL _fanConfig读取番值
- HandleDiscardReactions: 同优先级座位顺序
- 新增GetWinParams/CountWildcardsInHand辅助方法

验证: 47/47测试, Wuhan 1.6%胡牌(500局), Sichuan 0.4%

RuleEngine/AI/RandomMahjongAI.cs

@@ -35,13 +35,15 @@ public class RandomMahjongAI
         var chi = legalActions.FirstOrDefault(a => a.Action == "chi");
         if (chi != null) return ("chi", null);
 
-        // Discard: random tile
+        // Discard: random non-wildcard tile
         var discards = legalActions.Where(a => a.Action == "discard").ToList();
         if (discards.Count > 0)
         {
-            var chosen = discards[_rng.Next(discards.Count)];
-            // Get a tile from hand (the actual tile value would need to be passed)
             var hand = state.Hands.GetValueOrDefault(Name, new List<int>());
+            var nonWildTiles = hand.Where(t => !MahjongTile.IsWildcard(t)).ToList();
+            if (nonWildTiles.Count > 0)
+                return ("discard", nonWildTiles[_rng.Next(nonWildTiles.Count)]);
+            // Only wildcards left — discard one
             if (hand.Count > 0)
                 return ("discard", hand[_rng.Next(hand.Count)]);
         }