feat(desktop): 江南水乡河道横贯与波纹两帧

场景改为沿村蜿蜒水带（北岸凸湾、中段横贯、南段收窄），南北两岸石板路沿河展开，木桥三块纵跨全河连接民居门前石径；水面新增第二张波纹图块，按世界 tick/32 取模确定性交替，绘制无新增每帧分配。

3 files changed, 33 insertions, 15 deletions

diff --git a/src/LivingVillage.Desktop/Assets/jiangnan-world.png b/src/LivingVillage.Desktop/Assets/jiangnan-world.png
index 766405f..ca4a521 100644
--- a/src/LivingVillage.Desktop/Assets/jiangnan-world.png
+++ b/src/LivingVillage.Desktop/Assets/jiangnan-world.png
diff --git a/src/LivingVillage.Desktop/Game.fs b/src/LivingVillage.Desktop/Game.fs
index a5049f3..4871e80 100644
--- a/src/LivingVillage.Desktop/Game.fs
+++ b/src/LivingVillage.Desktop/Game.fs
@@ -576,6 +576,7 @@ type LivingVillageGame() as this =
                 viewport.Width
                 viewport.Height
                 renderPlan
+                world.Tick
                 profile.WorldTint
 
             let avatarSpec = VillageArt.avatarSpriteSpec avatarFacing world.Tick
diff --git a/src/LivingVillage.Desktop/VillageArt.fs b/src/LivingVillage.Desktop/VillageArt.fs
index 5883a97..a66474b 100644
--- a/src/LivingVillage.Desktop/VillageArt.fs
+++ b/src/LivingVillage.Desktop/VillageArt.fs
@@ -102,6 +102,7 @@ module VillageArt =
         | WallWoodSprite
         | WallWindowSprite
         | DoorSprite
+        | WaterSpriteB
 
     type private XnaColor = Microsoft.Xna.Framework.Color
     type private XnaRectangle = Microsoft.Xna.Framework.Rectangle
@@ -143,15 +144,7 @@ module VillageArt =
 
         { Origin = position 25 18
           Grounds =
-              [ ground Water 10 2
-                ground Water 10 3
-                ground Water 10 4
-                ground Water 10 5
-                ground Water 10 6
-                ground Water 10 7
-                ground Water 11 4
-                ground Water 11 5
-                ground StonePath 3 5
+              [ ground StonePath 3 5
                 ground StonePath 4 5
                 ground StonePath 5 5
                 ground StonePath 6 5
@@ -161,10 +154,26 @@ module VillageArt =
                 ground StonePath 10 5
                 ground StonePath 11 5
                 ground StonePath 6 6
-                ground StonePath 6 7 ]
+                ground StonePath 6 7
+                ground StonePath 6 8
+                ground StonePath 6 9
+                ground StonePath 6 10
+                for x in 0 .. 5 do
+                    ground StonePath x 11
+                for x in 9 .. 19 do
+                    ground StonePath x 11
+                for x in 1 .. 18 do
+                    ground StonePath x 14
+                ground Water 6 11
+                ground Water 7 11
+                ground Water 8 11
+                for x in 0 .. 19 do
+                    ground Water x 12
+                for x in 2 .. 17 do
+                    ground Water x 13 ]
           Props =
               [ renderProp House 6 5
-                renderProp Bridge 10 5
+                renderProp Bridge 6 11
                 renderProp BambooGrove 3 2
                 renderProp VegetablePatch 8 7 ]
           Interior =
@@ -190,7 +199,7 @@ module VillageArt =
                 [ for dx in -2 .. 1 do
                       for dy in -2 .. 0 do
                           yield position (x + dx) (y + dy) ]
-            | Bridge -> [ position x y; position x (y + 1) ]
+            | Bridge -> [ position x y; position x (y + 1); position x (y + 2) ]
             | BambooGrove -> [ position x y; position x (y + 1); position (x + 1) y ]
             | VegetablePatch -> [ position x y; position (x + 1) y ])
         |> many
@@ -212,6 +221,10 @@ module VillageArt =
     let animationFrame (tick: int64) : AnimationFrame =
         if positiveModulo64 8L tick < 4L then FrameOne else FrameTwo
 
+    /// Water surface ripple phase: flips every 32 simulation ticks, fully deterministic.
+    let waterFrameTick (tick: int64) : int =
+        int (positiveModulo64 2L (tick / 32L))
+
     let directionFromVector (vector: Vec2) : FacingDirection =
         if abs vector.X < 0.001f && abs vector.Y < 0.001f then
             SouthFacing
@@ -271,7 +284,7 @@ module VillageArt =
     let characterAtlasRelativePath = "Assets/jiangnan-characters.png"
     let interiorAtlasRelativePath = "Assets/jiangnan-interior.png"
 
-    let worldTileCount = 13
+    let worldTileCount = 14
     let worldAtlasWidth = Sim.tilePixels * worldTileCount
     let worldAtlasHeight = Sim.tilePixels
     let characterAtlasWidth = 32 * 4 * 4 * 2
@@ -313,6 +326,7 @@ module VillageArt =
             | WallWoodSprite -> 10
             | WallWindowSprite -> 11
             | DoorSprite -> 12
+            | WaterSpriteB -> 13
         XnaRectangle(index * Sim.tilePixels, 0, Sim.tilePixels, Sim.tilePixels)
 
     let private tilePosition x y : TilePosition =
@@ -350,9 +364,11 @@ module VillageArt =
         (viewportWidth: int)
         (viewportHeight: int)
         (plan: JiangnanRenderPlan)
+        (tick: int64)
         (tint: XnaColor) =
         let draw position sprite =
             drawWorldTile spriteBatch textures camera viewportWidth viewportHeight position sprite tint
+        let rippleFrame = waterFrameTick tick
 
         let tx0 = max 0 (int camera.X / Sim.tilePixels)
         let ty0 = max 0 (int camera.Y / Sim.tilePixels)
@@ -366,7 +382,7 @@ module VillageArt =
             let position = worldTile plan localPosition
             let sprite =
                 match kind with
-                | Water -> WaterSprite
+                | Water -> if rippleFrame = 0 then WaterSprite else WaterSpriteB
                 | StonePath -> StonePathSprite
             draw position sprite
 
@@ -383,7 +399,8 @@ module VillageArt =
         let drawBridge localPosition =
             let position = worldTile plan localPosition
             draw position BridgeSprite
-            draw (offsetTile position 1 0) BridgeSprite
+            draw (offsetTile position 0 1) BridgeSprite
+            draw (offsetTile position 0 2) BridgeSprite
 
         let drawBamboo localPosition =
             let position = worldTile plan localPosition