feat(mapgen): 默认可玩世界接入生成器 + 河景细节（P20 第三步 B）

- Game：默认 256x192 生成器世界（核心可达区站位），LV_LEGACY_MAP=1 /
  LV_MAP_SCALE>1 / LV_MAP_TOUR=1 回退旧路径；StartNewGame 走同一站位。
- VillageArt.drawWorld 新增 pixel 与 mapGen option：Some 时按生成器瓦片绘地面
  并叠加桥面/沿河民居/门，跳过 64x48 样例平面与道具；水波沿用 waterFrameTickAt。
- 新增 bridgeLanternTiles；夜间 LanternGlow 沿用既有预乘同心圆（无过曝白芯），
  生成器世界用桥头灯笼。
- 新增 LV_RIVERSCAPE_TOUR 真走位巡游与 LV_RECORD_NAME 录屏前缀（证据用）。

1 files changed, 67 insertions, 41 deletions

diff --git a/src/LivingVillage.Desktop/VillageArt.fs b/src/LivingVillage.Desktop/VillageArt.fs
index 19c9aa6..3ad5b19 100644
--- a/src/LivingVillage.Desktop/VillageArt.fs
+++ b/src/LivingVillage.Desktop/VillageArt.fs
@@ -600,13 +600,48 @@ module VillageArt =
     let private offsetTile (position: TilePosition) dx dy : TilePosition =
         tilePosition (position.X + dx) (position.Y + dy)
 
+    let private fillRect (spriteBatch: SpriteBatch) (pixel: Texture2D) (color: XnaColor) (x: int) (y: int) (w: int) (h: int) =
+        spriteBatch.Draw(pixel, XnaRectangle(x, y, max 1 w, max 1 h), color)
+
+    /// 生成器世界里的桥面与沿河民居（白墙黑瓦色块 + 门）；坐标由调用方按相机换算。
+    let private drawMapStructures
+        (spriteBatch: SpriteBatch)
+        (textures: ArtTextures)
+        (pixel: Texture2D)
+        (tileX: int -> int)
+        (tileY: int -> int)
+        (cell: int)
+        (map: MapGen.Result) =
+        let bridgeSource = tileSourceRectangle BridgeSprite
+        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
+            for row in building.Top .. building.Top + building.Height - 1 do
+                // 白墙朝向道路一行（门所在行），其余为黑瓦屋顶，两侧河岸朝向一致。
+                let color =
+                    if row = building.DoorY then XnaColor(236, 232, 220)
+                    else XnaColor(48, 52, 60)
+                fillRect spriteBatch pixel color (tileX building.Left) (tileY row) (building.Width * cell) (cell)
+            fillRect spriteBatch pixel (XnaColor(96, 60, 42)) (tileX building.DoorX) (tileY building.DoorY) cell cell
+
+    /// 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 =
+        map.Bridges
+        |> List.groupBy fst
+        |> List.collect (fun (x, entries) ->
+            let ys = entries |> List.map snd
+            [ (x, List.min ys); (x, List.max ys) ])
+        |> List.distinct
+
     let drawWorld
         (spriteBatch: SpriteBatch)
         (textures: ArtTextures)
+        (pixel: Texture2D)
         (camera: XnaVector2)
         (viewportWidth: int)
         (viewportHeight: int)
         (plan: JiangnanRenderPlan)
+        (mapGen: MapGen.Result option)
         (tick: int64)
         (tint: XnaColor) =
         let draw position sprite =
@@ -622,26 +657,30 @@ module VillageArt =
 
         // Procedural terrain for the 512x384 large world: water/pebble/peat codes map
         // onto the jiangnan atlas sprites with deterministic ripple continuity.
+        // 生成器世界：1 水 / 2 石板路 / 3 泥炭 / 0 草地。泥炭按草地渲染，路走石板贴图。
         let drawTerrainTile (position: TilePosition) (code: int) =
             match code with
             | 1 -> draw position (waterSpriteAt position)
             | 2 -> draw position StonePathSprite
-            | 3 -> draw position StonePathSprite
             | _ -> draw position GrassSprite
 
         let drawBaseTile (position: TilePosition) =
-            match ProceduralMap.terrainOption, ProceduralMap.bigWorldActive with
-            | (Some terrain, true) ->
-                let tx, ty = position.X, position.Y
-                let code = terrain.Tiles.[ty * ProceduralMap.width + tx]
-                drawTerrainTile position code
-            | _ ->
+            match mapGen with
+            | Some map ->
+                drawTerrainTile position map.Tiles.[position.Y * map.Width + position.X]
+            | None ->
+                match ProceduralMap.terrainOption, ProceduralMap.bigWorldActive with
+                | (Some terrain, true) ->
+                    let tx, ty = position.X, position.Y
+                    let code = terrain.Tiles.[ty * ProceduralMap.width + tx]
+                    drawTerrainTile position code
+                | _ ->
+                    match textures.Cc0TileAtlas with
+                    | Some cc0 -> drawCc0Tile spriteBatch cc0 tint (cc0GroundRect position) (position.X * Sim.tilePixels - int camera.X) (position.Y * Sim.tilePixels - int camera.Y)
+                    | None -> draw position GrassSprite
                 match textures.Cc0TileAtlas with
                 | Some cc0 -> drawCc0Tile spriteBatch cc0 tint (cc0GroundRect position) (position.X * Sim.tilePixels - int camera.X) (position.Y * Sim.tilePixels - int camera.Y)
                 | None -> draw position GrassSprite
-            match textures.Cc0TileAtlas with
-            | Some cc0 -> drawCc0Tile spriteBatch cc0 tint (cc0GroundRect position) (position.X * Sim.tilePixels - int camera.X) (position.Y * Sim.tilePixels - int camera.Y)
-            | None -> draw position GrassSprite
 
         let tx0, ty0, tx1, ty1 =
             MapGen.visibleTileRange Sim.mapWidthTiles Sim.mapHeightTiles (int camera.X) (int camera.Y) viewportWidth viewportHeight
@@ -649,7 +688,19 @@ module VillageArt =
             for x in tx0 .. tx1 do
                 drawBaseTile (tilePosition x y)
 
-        for localPosition, kind in plan.Grounds do
+        // 生成器世界：叠加桥面、沿河民居、桥头灯笼；不再绘制 64x48 样例平面与道具。
+        match mapGen with
+        | Some map ->
+            let mapTileX x = x * Sim.tilePixels - int camera.X
+            let mapTileY y = y * Sim.tilePixels - int camera.Y
+            drawMapStructures spriteBatch textures pixel mapTileX mapTileY Sim.tilePixels map
+            for (lanternX, lanternY) in bridgeLanternTiles map do
+                draw (tilePosition lanternX lanternY) LanternSprite
+        | None -> ()
+
+        // 回退（64x48 样例世界）或 LV_MAP_SCALE 大世界时仍绘制样例地面/道具。
+        let planGrounds = match mapGen with Some _ -> [] | None -> plan.Grounds
+        for localPosition, kind in planGrounds do
             let position = worldTile plan localPosition
             match kind with
             | Water -> draw position (waterSpriteAt position)
@@ -693,7 +744,8 @@ module VillageArt =
         let drawSingleTile localPosition sprite =
             draw (worldTile plan localPosition) sprite
 
-        for prop in plan.Props do
+        let planProps = match mapGen with Some _ -> [] | None -> plan.Props
+        for prop in planProps do
             match prop.Kind with
             | House -> drawHouse prop.Position
             | Bridge -> drawBridge prop.Position
@@ -717,37 +769,13 @@ module VillageArt =
             | 0 -> SmokeSpriteA
             | 1 -> SmokeSpriteB
             | _ -> SmokeSpriteC
-        for prop in plan.Props do
+        for prop in planProps do
             match prop.Kind with
             | House -> draw (offsetTile (worldTile plan prop.Position) 0 -3) smokeSprite
             | _ -> ()
 
     /// P20 证据用：把整张 MapGen 地图等比缩放到视口内绘制，返回绘制的瓦片数。
     /// 仅用于 `LV_MAPGEN_SHOT` 整图取证，不参与正常游戏循环。
-    let private fillRect (spriteBatch: SpriteBatch) (pixel: Texture2D) (color: XnaColor) (x: int) (y: int) (w: int) (h: int) =
-        spriteBatch.Draw(pixel, XnaRectangle(x, y, max 1 w, max 1 h), color)
-
-    /// 整图证据里叠加桥面与沿河民居（白墙黑瓦色块 + 门）。
-    let private drawMapStructures
-        (spriteBatch: SpriteBatch)
-        (textures: ArtTextures)
-        (pixel: Texture2D)
-        (tileX: int -> int)
-        (tileY: int -> int)
-        (cell: int)
-        (map: MapGen.Result) =
-        let bridgeSource = tileSourceRectangle BridgeSprite
-        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
-            for row in building.Top .. building.Top + building.Height - 1 do
-                // 白墙朝向道路一行（门所在行），其余为黑瓦屋顶，两侧河岸朝向一致。
-                let color =
-                    if row = building.DoorY then XnaColor(236, 232, 220)
-                    else XnaColor(48, 52, 60)
-                fillRect spriteBatch pixel color (tileX building.Left) (tileY row) (building.Width * cell) (cell)
-            fillRect spriteBatch pixel (XnaColor(96, 60, 42)) (tileX building.DoorX) (tileY building.DoorY) cell cell
-
     let drawMapFitted
         (spriteBatch: SpriteBatch)
         (textures: ArtTextures)
@@ -767,8 +795,7 @@ module VillageArt =
         let spriteOf code =
             match code with
             | 1 -> WaterSprite
-            | 2
-            | 3 -> StonePathSprite
+            | 2 -> StonePathSprite
             | _ -> GrassSprite
         for y in 0 .. map.Height - 1 do
             for x in 0 .. map.Width - 1 do
@@ -799,8 +826,7 @@ module VillageArt =
                 | 0 -> WaterSprite
                 | 1 -> WaterSpriteB
                 | _ -> WaterSpriteC
-            | 2
-            | 3 -> StonePathSprite
+            | 2 -> StonePathSprite
             | _ -> GrassSprite
         let mutable drawn = 0
         for y in y0 .. y1 do