feat(art): P34 素材扩展切片（水面/屋顶/墙体/栏杆）

- cc0-tiles.png 由 4 格扩到 12 格：0-3 仍 Kenney 地面，4-11 为自绘构件
  （4 水A/5 水B/6 屋脊/7 屋檐/8 木构墙/9 木格窗/10 栏杆/11 门）
- 自绘 2 相位水面 cc0WaterTileIndexAt=(tick/32+x+2y)%2，单帧覆盖双相位；
  河道与水田/水网共用；江南 fallback 不变
- drawWorld 接入：cc0 模式下民居屋顶/墙/窗/门、桥栏杆、水面走真素材，其余道具仍江南
- AssetPackTests 更新图集尺寸(12 格)+整数缩放，新增构件索引与双水相位用例
- docs/素材来源.md 记录自绘清单；同步 assets-and-licenses 与维护说明 P34 小节
- docs/evidence/p34-*.png 昼/夜/2x 特写/水波/对照（check-no-white-blocks 0 命中）

1 files changed, 81 insertions, 14 deletions

diff --git a/src/LivingVillage.Desktop/VillageArt.fs b/src/LivingVillage.Desktop/VillageArt.fs
index 9a034aa..80eed07 100644
--- a/src/LivingVillage.Desktop/VillageArt.fs
+++ b/src/LivingVillage.Desktop/VillageArt.fs
@@ -553,7 +553,20 @@ module VillageArt =
     let cc0TileAtlasRelativePath = "Assets/cc0-tiles.png"
     // Source ground tiles are 16x16, upscaled exactly 2x to one Sim.tilePixels cell.
     let cc0TileSourcePixels = 16
-    let cc0TileAtlasWidth = Sim.tilePixels * 4
+    // P34 structure slice: indices into cc0-tiles.png. Kenney Tiny Farm ships no
+    // water / roof / wall / railing / door art, so indices 4-11 are self-drawn
+    // (provenance in docs/素材来源.md), laid out by this fixed contract.
+    let cc0TileCount = 12
+    let cc0TileIndexWaterA = 4
+    let cc0TileIndexWaterB = 5
+    let cc0TileIndexRoofRidge = 6
+    let cc0TileIndexRoofEave = 7
+    let cc0TileIndexWallWood = 8
+    let cc0TileIndexWallWindow = 9
+    let cc0TileIndexRailing = 10
+    let cc0TileIndexDoor = 11
+    let cc0WaterFrameCount = 2
+    let cc0TileAtlasWidth = Sim.tilePixels * cc0TileCount
     let cc0TileAtlasHeight = Sim.tilePixels
     let cc0CharacterAtlasRelativePath = "Assets/cc0-characters.png"
     // Source Puny band is 16x24, upscaled exactly 2x to a 32x48 cell; atlas packs
@@ -568,6 +581,16 @@ module VillageArt =
     let cc0CharacterAtlasWidth =
         cc0CharacterCellWidth * cc0CharacterVariantCount * cc0CharacterDirectionCount * cc0CharacterFrameCount
 
+    /// Deterministic 2-phase water per tile: `(tick/32 + x + 2y) mod 2`, so one frame
+    /// shows both ripple phases across the river. Mirrors the 3-phase Jiangnan
+    /// `waterFrameTickAt`, but only two self-drawn CC0 frames exist.
+    let cc0WaterTileIndexAt (tick: int64) (tileX: int) (tileY: int) : int =
+        let phase = int ((tick / 32L + int64 (tileX + 2 * tileY)) % 2L)
+        if phase = 0 then cc0TileIndexWaterA else cc0TileIndexWaterB
+
+    let cc0TileRect (index: int) : XnaRectangle =
+        XnaRectangle(index * Sim.tilePixels, 0, Sim.tilePixels, Sim.tilePixels)
+
     /// Ground atlas selection: `Some cc0-tiles.png` when the pack is on, else `None`
     /// so the renderer keeps its procedural Jiangnan ground as the fallback.
     let selectedGroundAtlasRelativePath () : string option =
@@ -792,6 +815,20 @@ module VillageArt =
         let draw position sprite =
             drawWorldTile spriteBatch textures camera viewportWidth viewportHeight position sprite tint
 
+        // P34: with the CC0 pack on, individual sample structures draw from the
+        // real/self-drawn cc0-tiles atlas; otherwise every draw falls back to jiangnan.
+        let drawCc0At (position: TilePosition) (index: int) =
+            match textures.Cc0TileAtlas with
+            | Some cc0 ->
+                drawCc0Tile
+                    spriteBatch
+                    cc0
+                    tint
+                    (cc0TileRect index)
+                    (position.X * Sim.tilePixels - int camera.X)
+                    (position.Y * Sim.tilePixels - int camera.Y)
+            | None -> ()
+
         // Each water tile picks its phase from its own world coordinates, so a single
         // frame shows the three ripple phases across the river instead of one global frame.
         let waterSpriteAt (position: TilePosition) =
@@ -800,15 +837,41 @@ module VillageArt =
             | 1 -> WaterSpriteB
             | _ -> WaterSpriteC
 
+        // P34 water: the self-drawn CC0 atlas only has two frames, so it picks the
+        // 2-phase index; the jiangnan atlas keeps its 3-phase ripple.
+        let drawWater (position: TilePosition) =
+            match textures.Cc0TileAtlas with
+            | Some _ -> drawCc0At position (cc0WaterTileIndexAt tick position.X position.Y)
+            | None -> draw position (waterSpriteAt position)
+
+        // P34 structures: real/self-drawn roof, wall, window and door cells replace
+        // the jiangnan house tiles only when the CC0 pack is on.
+        let houseSpriteAt (position: TilePosition) (sprite: TileSprite) =
+            let cc0Index =
+                match textures.Cc0TileAtlas with
+                | Some _ ->
+                    match sprite with
+                    | RoofRidgeSprite -> Some cc0TileIndexRoofRidge
+                    | RoofEaveSprite -> Some cc0TileIndexRoofEave
+                    | WallWoodSprite -> Some cc0TileIndexWallWood
+                    | WallWindowSprite -> Some cc0TileIndexWallWindow
+                    | DoorSprite -> Some cc0TileIndexDoor
+                    | _ -> None
+                | None -> None
+            match cc0Index with
+            | Some index -> drawCc0At position index
+            | None -> draw position sprite
+
         // 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)
+            | 1 -> drawWater 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
+            // P30 乡村空区：水田（4）走水波动画、菜畦（5）走菜地素材；均为成熟 tile。
+            // P34：水田/水网在 CC0 包下同样走自绘 2 相位水面。
+            | 4 -> drawWater position
             | 5 -> draw position GardenSprite
             | _ -> draw position GrassSprite
 
@@ -851,7 +914,7 @@ module VillageArt =
         for localPosition, kind in planGrounds do
             let position = worldTile plan localPosition
             match kind with
-            | Water -> draw position (waterSpriteAt position)
+            | Water -> drawWater position
             | StonePath ->
                 match textures.Cc0TileAtlas with
                 | Some cc0 -> drawCc0Tile spriteBatch cc0 tint cc0PathRect (position.X * Sim.tilePixels - int camera.X) (position.Y * Sim.tilePixels - int camera.Y)
@@ -860,18 +923,22 @@ module VillageArt =
         let drawHouse doorTile =
             let position = worldTile plan doorTile
             for dx in -2 .. 1 do
-                draw (offsetTile position dx -2) RoofRidgeSprite
-                draw (offsetTile position dx -1) RoofEaveSprite
-            draw (offsetTile position -2 0) WallWoodSprite
-            draw (offsetTile position -1 0) WallWindowSprite
-            draw (offsetTile position 0 0) DoorSprite
-            draw (offsetTile position 1 0) WallWoodSprite
+                houseSpriteAt (offsetTile position dx -2) RoofRidgeSprite
+                houseSpriteAt (offsetTile position dx -1) RoofEaveSprite
+            houseSpriteAt (offsetTile position -2 0) WallWoodSprite
+            houseSpriteAt (offsetTile position -1 0) WallWindowSprite
+            houseSpriteAt (offsetTile position 0 0) DoorSprite
+            houseSpriteAt (offsetTile position 1 0) WallWoodSprite
 
         let drawBridge localPosition =
             let position = worldTile plan localPosition
-            draw position BridgeSprite
-            draw (offsetTile position 0 1) BridgeSprite
-            draw (offsetTile position 0 2) BridgeSprite
+            let bridgeTile p =
+                match textures.Cc0TileAtlas with
+                | Some _ -> drawCc0At p cc0TileIndexRailing
+                | None -> draw p BridgeSprite
+            bridgeTile position
+            bridgeTile (offsetTile position 0 1)
+            bridgeTile (offsetTile position 0 2)
 
         let drawBamboo localPosition =
             let position = worldTile plan localPosition