fix: IdentifyFans filter排除无fallback番型—防止跨变体越权

核心变更:
- filter从'well-known全放行'改为'只放行_fanConfig或有fallback值的'
- 排除: 断幺九/无字/缺一门/将/平胡/平和(无hardcoded fallback)
- 这些被排除时→allZeroValue→鸡胡兜底→保证非零分

效果: 南昌不再显示'断幺九+无字+平胡'等不存在于南昌规则的番型
测试: _fanConfig补全16个番型, 58 tests pass

RuleEngine.Tests/CoreTests.cs

@@ -90,7 +90,25 @@ public class DeckTests
 
 public class MeldsSolverTests
 {
-    private readonly MeldsSolver _solver = new(new Dictionary<string, FanConfig>());
+    private readonly MeldsSolver _solver = new(new Dictionary<string, FanConfig>
+    {
+        ["清一色"] = new() { BaseFan = 24 },
+        ["混一色"] = new() { BaseFan = 6 },
+        ["字一色"] = new() { BaseFan = 64 },
+        ["对对胡"] = new() { BaseFan = 2 },
+        ["碰碰和"] = new() { BaseFan = 6 },
+        ["暗七对"] = new() { BaseFan = 8 },
+        ["带幺九"] = new() { BaseFan = 2 },
+        ["缺一门"] = new() { BaseFan = 0 },
+        ["平胡"] = new() { BaseFan = 0 },
+        ["断幺九"] = new() { BaseFan = 2 },
+        ["无字"] = new() { BaseFan = 0 },
+        ["全大"] = new() { BaseFan = 12 },
+        ["全中"] = new() { BaseFan = 12 },
+        ["全小"] = new() { BaseFan = 12 },
+        ["全双"] = new() { BaseFan = 24 },
+        ["鸡胡"] = new() { BaseFan = 1 },
+    });
 
     // === 标准胡牌 ===
     [Fact]

RuleEngine/Patterns/MeldsSolver.cs

@@ -808,15 +808,16 @@ public class MeldsSolver
         if (fans.Count == 0 || allZeroValue)
             fans.Add("鸡胡");
 
-        // Filter: only keep fans that exist in DSL config or are well-known
+        // Filter: keep fans in _fanConfig OR event fans OR well-known structural fans
+        // Exclude zero-value markers (无字/缺一门/将) and no-fallback fans (断幺九/平胡/平和)
+        // → these trigger allZeroValue→鸡胡 to ensure non-zero scoring
         return fans.Where(f => _fanConfig.ContainsKey(f) ||
-            f is "清一色" or "混一色" or "对对胡" or "碰碰和" or "暗七对" or "七对"
+            f is "杠上开花" or "海底捞月" or "抢杠胡" or "天胡" or "地胡" or "癞子胡"
-                or "带幺九" or "十三幺" or "字一色" or "断幺九" or "无字" or "将"
+                or "清一色" or "混一色" or "对对胡" or "碰碰和" or "暗七对" or "七对" or "带幺九" or "十三幺" or "鸡胡" or "字一色"
-                or "缺一门" or "平胡" or "全大" or "全中" or "全小" or "全双"
+                or "全大" or "全中" or "全小" or "全双" or "大于五" or "小于五"
-                or "将一色" or "大四喜" or "大三元" or "小四喜" or "小三元" or "三风" or "双箭刻"
+                or "将一色" or "大四喜" or "大三元" or "小四喜" or "小三元"
                 or "一色四同顺" or "一色三同顺" or "一般高" or "五门齐" or "全求人" or "门前清"
-                or "鸡胡" or "癞子胡" or "平和"
+                or "三风" or "双箭刻" or "圈风" or "门风" or "单钓将" or "四归一" or "连七对" or "全不靠" or "一色双龙会").ToList();
-                or "圈风" or "门风" or "单钓将" or "四归一" or "杠上开花" or "海底捞月" or "抢杠胡" or "天胡" or "地胡").ToList();
     }
 
     // === 番型互斥应用 ===