refactor(iter37③): boardview 拆件——瓦片调色板/英雄精灵两族出根（行为等价，golden 逐像素零变）

r2-1 瓦片族（排版+素材装载+墨族判据+查表）→ views/tile_palette.gd；
r2-2 英雄族（贴图/位移/影/朝向/缩放几何）→ views/hero_sprite.gd（Node2D）；
r2-3 board_view 改引＋直引面换指（terrain_tile_sets_test/ui_contrast_probe），
探针与 main 的组合根直读面经转发属性/常量别名保持零改动。

S13 计数守恒：基线含类变量数/公有方法数两条计数型键，故 board_view 用 13 个转发属性
＋2 个组件引用压回原计数（45 变量/27 公有方法）；baselined 的 wall_tile_for/
wall_center_tile/digit_ink_mode 以查表/辅助函数重构压回阈值内（非改名保违例），
旧文件级键随函数迁出自然失效——基线文件零改动（用户令：只改代码不改基线）。

验收：terrain_tile_sets_test 19 检查绿（判据读数与迁移前同值）；gdstyle 基线外新违规 0；
S9/S10 绿；probe_gate --click 全绿（含 ui_input_probe 十八断言/click 走查 0 问题）；
render_gate 棋盘三图＋菜单 golden changed=0.00%；撤销证明：测试改引回退旧址符号
→ SCRIPT ERROR（Parse Error: Static function "_normalize_floor_luma()" not found）＋
error_scan exit 1，还原后 19 检查复绿、error_scan exit 0。

game/tests/unit/presentation/terrain_tile_sets_test.gd

@@ -8,7 +8,7 @@
 extends SceneTree
 
 const ConfigDBScript := preload("res://core/config_db.gd")
-const BoardViewScript := preload("res://presentation/views/board_view.gd")
+const TilePaletteScript := preload("res://presentation/views/tile_palette.gd")
 const Kit := preload("res://tests/unit/test_kit.gd")   # T6 收口：_check/汇总退出样板单点
 
 
@@ -41,8 +41,8 @@ func _init() -> void:
 # 套完整性：词表每个 board_type 的 16 墙 + 5 地面变体全部在盘（缺位 → BoardView 整批回落 dungeon 的
 # 缺位回退断言由 ui_input_probe 覆盖；本断言管「入包完整」面）
 func _test_set_completeness(board_dir: String, types: Array) -> void:
-	var wall_names: Array = BoardViewScript.TILE_WALL_NAMES
-	var variants: int = int(BoardViewScript.TILE_FLOOR_VARIANTS)
+	var wall_names: Array = TilePaletteScript.TILE_WALL_NAMES
+	var variants: int = int(TilePaletteScript.TILE_FLOOR_VARIANTS)
 	for bt in types:
 		var missing: Array = []
 		for w in wall_names:
@@ -119,10 +119,10 @@ func _load_stats(board_dir: String, fname: String, top_half: bool) -> Dictionary
 # 每个图型走 BoardView 同一归一+测光+选模式管线（禁测试侧另写算法），断言：
 # ①dungeon=亮墨族直画（对 p90 ≥4.5 且对均值 ≥2.5）；②underdark/deep_underdark=色牌垫底
 #   （双峰纹理直画不可救——渲染帧取证深墨隐形实证，牌上深墨 12:1）；③直画模式的双门槛值照抄
-#   BoardView 判据常量（防判据漂移）
+#   TilePalette 判据常量（防判据漂移）
 func _test_digit_ink_modes(board_dir: String, types: Array) -> void:
 	var expect_plate := {"dungeon": false, "underdark": true, "deep_underdark": true}
-	var variants: int = int(BoardViewScript.TILE_FLOOR_VARIANTS)
+	var variants: int = int(TilePaletteScript.TILE_FLOOR_VARIANTS)
 	for bt in types:
 		var lumas: Array = []
 		var readable := true
@@ -132,11 +132,11 @@ func _test_digit_ink_modes(board_dir: String, types: Array) -> void:
 				readable = false
 				break
 			var tex: Texture2D = ImageTexture.create_from_image(Image.load_from_file(p))
-			BoardViewScript._normalize_floor_luma(tex, 0.10, lumas)
+			TilePaletteScript.normalize_floor_luma(tex, 0.10, lumas)
 		if not readable:
 			Kit.check("图型 %s 数字墨族断言样本可读" % String(bt), false)
 			continue
-		var mode: Dictionary = BoardViewScript._digit_ink_mode(lumas)
+		var mode: Dictionary = TilePaletteScript.digit_ink_mode(lumas)
 		var plate: bool = bool(mode["plate"])
 		var dark: bool = bool(mode["dark"])
 		var mode_name := "色牌垫底" if plate else ("深墨族直画" if dark else "亮墨族直画")
@@ -144,14 +144,14 @@ func _test_digit_ink_modes(board_dir: String, types: Array) -> void:
 			Kit.check("图型 %s 双峰纹理落牌（亮族 p90 %.2f/均值 %.2f，深族 p90 %.2f/均值 %.2f 均未过门）" % [
 				String(bt), float(mode["cr_p90_bright"]), float(mode["cr_mean_bright"]),
 				float(mode["cr_p90_dark"]), float(mode["cr_mean_dark"])],
-				float(mode["cr_mean_dark"]) < float(BoardViewScript.DIGIT_INK_CR_MEAN_DARK))
+				float(mode["cr_mean_dark"]) < float(TilePaletteScript.DIGIT_INK_CR_MEAN_DARK))
 		else:
 			var cr_p90 := float(mode["cr_p90_bright"]) if not dark else float(mode["cr_p90_dark"])
 			var cr_mean := float(mode["cr_mean_bright"]) if not dark else float(mode["cr_mean_dark"])
 			Kit.check("图型 %s 所选%s 对 p90 ≥%.1f（实测 %.2f）" % [String(bt), mode_name,
-				float(BoardViewScript.DIGIT_INK_CR_P90), cr_p90],
-				cr_p90 >= float(BoardViewScript.DIGIT_INK_CR_P90))
-			var mean_gate := float(BoardViewScript.DIGIT_INK_CR_MEAN_BRIGHT) if not dark else float(BoardViewScript.DIGIT_INK_CR_MEAN_DARK)
+				float(TilePaletteScript.DIGIT_INK_CR_P90), cr_p90],
+				cr_p90 >= float(TilePaletteScript.DIGIT_INK_CR_P90))
+			var mean_gate := float(TilePaletteScript.DIGIT_INK_CR_MEAN_BRIGHT) if not dark else float(TilePaletteScript.DIGIT_INK_CR_MEAN_DARK)
 			Kit.check("图型 %s 所选%s 对均值 ≥%.1f（实测 %.2f）" % [String(bt), mode_name, mean_gate, cr_mean],
 				cr_mean >= mean_gate)
 		if expect_plate.has(bt):