feat(art): P33 接入 CC0 真实像素素材样板（地面+角色竖直切片）

- 修复 make-cc0-art.py 地块取样间距：packed sheet 无间距(16px pitch)，旧 17px 误采错格
- 重选草地/石板格 (9,8)/(10,8)/(4,8)/(4,9)，整数 2x NEAREST 重建 cc0-tiles.png
- VillageArt 暴露 selectedGround/CharacterAtlasRelativePath 纯函数，保留 LV_ASSET_PACK=cc0
  开关与程序绘制江南图集 fallback
- 新增 AssetPackTests：图集加载尺寸、整数倍缩放、开关/回退断言
- docs/素材来源.md 记录来源/许可/sha256/构建/开关；同步 assets-and-licenses 与维护说明 P33 小节
- docs/evidence/p33-atlas-*.png 昼/夜/2x 特写/程序绘制对照（check-no-white-blocks 0 命中）

1 files changed, 7 insertions, 4 deletions

diff --git a/scripts/make-cc0-art.py b/scripts/make-cc0-art.py
index f5c97ee..b26cba1 100644
--- a/scripts/make-cc0-art.py
+++ b/scripts/make-cc0-art.py
@@ -98,16 +98,19 @@ def verify_png(path, expected_w, expected_h):
 def build_cc0_tile_atlas():
     """Four 32x32 ground tiles from Kenney Tiny Farm, upscaled 2x.
 
-    Tile selection is fixed by grid coordinates chosen from the pack's
-    tilemap_packed.png (grass: two greens; stone path: pale slab; dirt: apricot).
+    Source is the *packed* sheet (tilemap_packed.png) which has NO spacing between
+    tiles: 192x176 = 12x11 tiles at a 16px pitch (the spaced tilemap.png is 203x186
+    at 17px pitch; mixing the two misaligns every non-zero cell). Tile selection is
+    fixed by grid coordinates: two full grass shades (9,8)/(10,8) for the checker
+    ground, then two grey stone slabs (4,8)/(4,9) for the paved path.
     """
     c = Canvas(128, 32)
     packed = Image.open(THIRD / "kenney_tiny-farm" / "Tilemap" / "tilemap_packed.png").convert("RGBA")
 
     def tile(grid_x, grid_y):
-        return packed.crop((grid_x * 17, grid_y * 17, grid_x * 17 + 16, grid_y * 17 + 16))
+        return packed.crop((grid_x * 16, grid_y * 16, grid_x * 16 + 16, grid_y * 16 + 16))
 
-    choices = [(10, 9), (9, 7), (6, 7), (6, 9)]
+    choices = [(9, 8), (10, 8), (4, 8), (4, 9)]
     for index, (gx, gy) in enumerate(choices):
         t = tile(gx, gy)
         c.blit(t, index * 32, 0, scale=2)