feat(desktop): P30 512 民居增密 + 乡村空区填充 + 主路柔化

- MapGen（仅大图尺寸自适应分支，默认 64x48/256x192 不进入、不消费额外 RNG）：
  ① ExtraRiversideHouses 16 -> 30，组团 2-5 座；含基础岸屋的路段优先布组并为每座孤立
     基础民居贴格配对，placeGroup 试排后按「与既有/同组民居足迹间隙 <=2」过滤，孤立单屋不落地。
     512 seed4242：组团民居 24 -> 45，规模 [5;4x6;3x2;2x3]，0 组 <2 座。
  ② 新增 GroundTile.PaddyField=4/VegetablePlot=5（成熟 tile；非水可通行）+ Result.Groves
     （纯视觉）+ Result.Farmhouses（门贴院落路、计入 BFS）；18x14 确定性网格铺田块/树丛/农舍，
     离水 >=3 格、避开路网/核心/民居。草地瓦片 96.3% -> 83.9%，水田 11595 + 菜畦 12877 格。
  ③ Result.MainRoadCenter 逐列中心线，value noise（scale 130、幅度 ±3）确定性缓弯，
     相邻列步长 <=1、遇弯补格保证 4 连通；默认图主街仍笔直。
- VillageArt：水田/菜畦/树丛/农舍渲染（复用成熟 sprite 与同一立面纯函数）、农舍门窗计入夜光、
  新增 drawMapRegion 局部真实离屏渲染。
- Game：P30 证据钩子 LV_MAPGEN_P30_SHOT=1（整图 3072x2304 day/night + 田块/主路 512x256@4px）。
- 回归 +5：组团规模/空区填充/田块合规/农舍可达确定性/主路确定性弯曲。
  Kernel 92 / Desktop 156 全绿；Release 0 警告 0 错误；
  final_digest=953775FAEB2F… 3 次一致、performance_determinism=PASS；
  64x48=6042052、256x192=1284656962 锁定不变。

1 files changed, 57 insertions, 2 deletions

diff --git a/src/LivingVillage.Desktop/VillageArt.fs b/src/LivingVillage.Desktop/VillageArt.fs
index 3e52546..4faa886 100644
--- a/src/LivingVillage.Desktop/VillageArt.fs
+++ b/src/LivingVillage.Desktop/VillageArt.fs
@@ -656,7 +656,7 @@ module VillageArt =
             spriteBatch.Draw(textures.TileAtlas, XnaRectangle(tileX x, tileY y, cell, cell), tileSourceRectangle sprite, XnaColor.White)
         for (x, y) in map.Bridges do
             spriteBatch.Draw(textures.TileAtlas, XnaRectangle(tileX x, tileY y, cell, cell), bridgeSource, XnaColor.White)
-        for building in map.Buildings do
+        let drawHouse (building: MapGen.Building) =
             let left = building.Left
             let right = building.Left + building.Width - 1
             match houseFacadeVariant building with
@@ -690,6 +690,11 @@ module VillageArt =
                     let wallSprite =
                         if x = building.DoorX then CourtyardDoorSprite else WallLatticeSprite
                     drawCell wallSprite x building.DoorY
+        for building in map.Buildings do
+            drawHouse building
+        // P30 散落农舍与沿河民居共用同一套立面纯函数。
+        for farmhouse in map.Farmhouses do
+            drawHouse farmhouse
         // P26 河岸装饰：护岸石垒 / 芦苇 / 垂柳（垂柳占上下两格），只在大图生成。
         for decoration in map.Decorations do
             match decoration.Kind with
@@ -698,6 +703,11 @@ module VillageArt =
             | MapGen.RiverDecorationKind.Willow ->
                 drawCell WillowTopSprite decoration.X decoration.Y
                 drawCell WillowBaseSprite decoration.X (decoration.Y + 1)
+        // P30 乡村树丛：竹丛 / 灌木丛（纯视觉，不写瓦片、不影响通行）。
+        for grove in map.Groves do
+            match grove.Kind with
+            | MapGen.BambooClump -> drawCell BambooSprite grove.X grove.Y
+            | MapGen.ShrubClump -> drawCell ShrubSprite grove.X grove.Y
 
     /// 桥头灯笼瓦片：每座桥每列的最上/最下一格（桥两端），用于挂灯笼与夜间暖光。
     let bridgeLanternTiles (map: MapGen.Result) : (int * int) list =
@@ -710,10 +720,11 @@ module VillageArt =
 
     /// P29 夜景灯光源瓦片：桥头灯笼 + 民居门窗暖光（确定性纯函数，便于单测）。
     /// 每户至少门格发光；变体 A 再取第一扇横向窗，变体 B（整面格栅窗）与门同格故不另加。
+    /// P30：散落农舍的门窗暖光一并计入。
     let nightLightTiles (map: MapGen.Result) : (int * int) list =
         let lanterns = bridgeLanternTiles map
         let houseLights =
-            map.Buildings
+            (map.Buildings @ map.Farmhouses)
             |> List.collect (fun building ->
                 let windowTiles =
                     if houseFacadeVariant building = 0 then
@@ -772,6 +783,9 @@ module VillageArt =
             match code with
             | 1 -> draw position (waterSpriteAt position)
             | 2 -> draw position StonePathSprite
+            // P30 乡村空区：水田（4）走静态水面素材、菜畦（5）走菜地素材；均为成熟 tile。
+            | 4 -> draw position WaterSprite
+            | 5 -> draw position GardenSprite
             | _ -> draw position GrassSprite
 
         let drawBaseTile (position: TilePosition) =
@@ -907,6 +921,9 @@ module VillageArt =
             match code with
             | 1 -> WaterSprite
             | 2 -> StonePathSprite
+            // P30 乡村空区：水田走静态水面、菜畦走菜地素材。
+            | 4 -> WaterSprite
+            | 5 -> GardenSprite
             | _ -> GrassSprite
         for y in 0 .. map.Height - 1 do
             for x in 0 .. map.Width - 1 do
@@ -942,6 +959,8 @@ module VillageArt =
                 | 1 -> WaterSpriteB
                 | _ -> WaterSpriteC
             | 2 -> StonePathSprite
+            | 4 -> WaterSprite
+            | 5 -> GardenSprite
             | _ -> GrassSprite
         let mutable drawn = 0
         for y in y0 .. y1 do
@@ -954,6 +973,42 @@ module VillageArt =
             drawNightGlows spriteBatch pixel map (4 * Sim.tilePixels) (int (150.0f * glowScale)) tileX tileY Sim.tilePixels
         drawn
 
+    /// P30 证据用：把地图的任意 tile 矩形 [tileX0,tileY0,tilesW,tilesH] 以 cell px/tile 真实
+    /// 离屏渲染到 target（含民居/田块/树丛/桥/河岸装饰与可选夜光），返回绘制瓦片数。
+    /// 与 drawMapFitted/drawMapViewport 共用 drawMapStructures / drawNightGlows 纯函数。
+    let drawMapRegion
+        (spriteBatch: SpriteBatch)
+        (textures: ArtTextures)
+        (pixel: Texture2D)
+        (tileX0: int)
+        (tileY0: int)
+        (tilesW: int)
+        (tilesH: int)
+        (cell: int)
+        (map: MapGen.Result)
+        (tint: XnaColor)
+        (glowScale: float32) : int =
+        let tileX x = (x - tileX0) * cell
+        let tileY y = (y - tileY0) * cell
+        let spriteOf code =
+            match code with
+            | 1 -> WaterSprite
+            | 2 -> StonePathSprite
+            | 4 -> WaterSprite
+            | 5 -> GardenSprite
+            | _ -> GrassSprite
+        let mutable drawn = 0
+        for y in tileY0 .. tileY0 + tilesH - 1 do
+            for x in tileX0 .. tileX0 + tilesW - 1 do
+                if x >= 0 && x < map.Width && y >= 0 && y < map.Height then
+                    let code = map.Tiles.[y * map.Width + x]
+                    spriteBatch.Draw(textures.TileAtlas, XnaRectangle(tileX x, tileY y, cell, cell), tileSourceRectangle (spriteOf code), tint)
+                    drawn <- drawn + 1
+        drawMapStructures spriteBatch textures pixel tileX tileY cell map
+        if glowScale > 0.0f then
+            drawNightGlows spriteBatch pixel map (4 * cell) (int (150.0f * glowScale)) tileX tileY cell
+        drawn
+
     let drawCharacter
         (spriteBatch: SpriteBatch)
         (textures: ArtTextures)