feat(desktop): P29 512 聚落组团 + 夜景灯光径向光晕

- MapGen：仅大图新增 ClusterSeed（group seeding）与组团布屋——512 沿横向石板路
  （主街+河岸路）成排成组：组内 2-4 座/1 格间隙、组间 4-6 格空档，宽度 2/3/4 分层；
  垂柳改为确定性成丛（2-3 株/丛、丛间 3-5 格空档）。独立 clusterRng 不触碰
  structureRng，默认图仍不消费 RNG，64x48=6042052 / 256x192=1284656962 锁定不变。
- VillageArt：新增 lanternFalloff（二次 1-(d/r)^2，半径 0 处最大、边缘 0、严格单调无平台）；
  lanternGlowLayers 按该衰减逐环累积 alpha；drawNightGlows 对桥头灯笼+民居门窗画半径
  4 tile 的柔和径向光晕，整图取证与实机 DrawWorldView 共用同一套纯函数。
- 回归 +6：组团行/成丛/衰减/光源确定性；Desktop 151、Kernel 92 全绿，Release 0/0，
  final_digest=953775FAEB2F… 3 次一致。证据帧见 art/p29-*。

1 files changed, 79 insertions, 0 deletions

diff --git a/src/LivingVillage.Desktop.Tests/MapGenTests.fs b/src/LivingVillage.Desktop.Tests/MapGenTests.fs
index b737707..d83a144 100644
--- a/src/LivingVillage.Desktop.Tests/MapGenTests.fs
+++ b/src/LivingVillage.Desktop.Tests/MapGenTests.fs
@@ -276,6 +276,85 @@ type MapGenTests () =
         Assert.AreEqual<int>(4, (MapGen.generateWithSize 64 48 (uint64 4242)).Buildings.Length)
         Assert.AreEqual<int>(4, (MapGen.generateWithSize 256 192 (uint64 4242)).Buildings.Length)
 
+    // ---- P29：512 聚落组团（group seeding 仅大图启用；行内成组、组间留档） ----
+
+    [<TestMethod>]
+    member _.ClusterSeedOnlyEnabledForLargeMaps () =
+        Assert.AreEqual<uint64>(0UL, (MapGen.paramsForSize 64 48 (uint64 4242)).ClusterSeed)
+        Assert.AreEqual<uint64>(0UL, (MapGen.paramsForSize 256 192 (uint64 4242)).ClusterSeed)
+        Assert.AreNotEqual<uint64>(0UL, (MapGen.paramsForSize 512 384 (uint64 4242)).ClusterSeed)
+        Assert.AreEqual<uint64>(0UL, (MapGen.defaultParams (uint64 4242)).ClusterSeed)
+
+    [<TestMethod>]
+    member _.LargeMapHousesFormClusteredRowsWithControlledGaps () =
+        let map = MapGen.generateWithSize 512 384 (uint64 4242)
+        let rowClusters (row: MapGen.Building list) =
+            let sorted = row |> List.sortBy (fun b -> b.Left)
+            let clusters = ResizeArray<MapGen.Building list>()
+            let mutable current: MapGen.Building list = []
+            let mutable previousEnd = System.Int32.MinValue
+            for building in sorted do
+                if current <> [] && building.Left - previousEnd <= 2 then
+                    current <- building :: current
+                else
+                    if current <> [] then clusters.Add(List.rev current)
+                    current <- [ building ]
+                previousEnd <- building.Left + building.Width - 1
+            if current <> [] then clusters.Add(List.rev current)
+            List.ofSeq clusters
+        let clusteredRows = map.Buildings |> List.groupBy (fun b -> b.Top) |> List.map (snd >> rowClusters)
+        let clusterSizes = clusteredRows |> List.collect (List.map List.length)
+        Assert.IsTrue(clusterSizes |> List.exists (fun n -> n >= 3), "at least one row-sized house cluster")
+        // 行内出现多个簇 => 组间留有可控空档，而不是一整排等距。
+        let rowCount = map.Buildings |> List.map (fun b -> b.Top) |> List.distinct |> List.length
+        Assert.IsTrue(clusterSizes.Length > rowCount, "rows must split into separated groups")
+        for clustersInRow in clusteredRows do
+            match clustersInRow with
+            | first :: rest ->
+                let mutable previous = first
+                for cluster in rest do
+                    let prevEnd = previous |> List.map (fun b -> b.Left + b.Width - 1) |> List.max
+                    let nextStart = cluster |> List.map (fun b -> b.Left) |> List.min
+                    Assert.IsTrue(nextStart - prevEnd >= 3, "groups must be separated by a controlled gap")
+                    previous <- cluster
+            | [] -> ()
+
+    /// 组团参数下，512 world 同 seed 两次生成逐字节一致（checksum 且序列化 diff 为空）。
+    [<TestMethod>]
+    member _.LargeMapClusterLayoutChecksumIsEmptyDiffAcrossRuns () =
+        let a = MapGen.generateWithSize 512 384 (uint64 4242)
+        let b = MapGen.generateWithSize 512 384 (uint64 4242)
+        Assert.IsTrue(a.Tiles = b.Tiles, "tiles must be byte-identical across runs")
+        Assert.AreEqual<int64>(checksum a, checksum b)
+        Assert.AreEqual<string>(MapGen.serialize a, MapGen.serialize b)
+        Assert.IsTrue(a.Buildings = b.Buildings)
+        Assert.IsTrue(a.Decorations = b.Decorations)
+
+    /// P29 垂柳成丛：岸边出现相邻 2-3 株的柳丛，且不再是均匀逐格散布。
+    [<TestMethod>]
+    member _.LargeMapWillowsGrowInGroves () =
+        let map = MapGen.generateWithSize 512 384 (uint64 4242)
+        let willows = map.Decorations |> List.filter (fun d -> d.Kind = MapGen.Willow)
+        Assert.IsTrue(willows.Length > 0, "large map must place willows")
+        let groveSizes =
+            willows
+            |> List.groupBy (fun d -> d.Y)
+            |> List.collect (fun (_, row) ->
+                let xs = row |> List.map (fun d -> d.X) |> List.sort
+                let sizes = ResizeArray<int>()
+                let mutable current = 0
+                let mutable previous = System.Int32.MinValue
+                for x in xs do
+                    if previous >= 0 && x - previous = 1 then
+                        current <- current + 1
+                    else
+                        if current > 0 then sizes.Add current
+                        current <- 1
+                    previous <- x
+                if current > 0 then sizes.Add current
+                List.ofSeq sizes)
+        Assert.IsTrue(groveSizes |> List.exists (fun n -> n >= 2), "willows must form groves of adjacent trunks")
+
     // ---- P25：大图不产孤立石板 tile（装饰石块默认开启仅限小图） ----
 
     [<TestMethod>]