GPU art: drop the diagonal stub at the end of the accent stripe; appraisal test helpers

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

art/big.py

@@ -167,8 +167,6 @@ def gpu_front(accent, accent_dark, brand_text, burnt=False):
     # 前沿斜切装饰条：品牌色 + 品牌字
     for x in range(x0 + 4, x1 - 20):
         c.rect(x, y1 - 5, x, y1 - 3, accent if x % 11 else accent_dark)
-    for k in range(18):
-        c.rect(x0 + 4 + k, y1 - 5 - k // 2, x0 + 4 + k, y1 - 3 - k // 2 + 1, accent)
     text57(c, 112, 84, brand_text, 'h')
     # 顶沿：四根铜热管端头与 8 针供电口
     for i in range(4):
@@ -283,8 +281,6 @@ def gpu_back(accent, accent_dark, burnt=False):
     for x in range(x0 + 4, x1 - 4):
         c.rect(x, 56, x, 59, accent)
         c.put(x, 60, accent_dark)
-    for k in range(20):
-        c.rect(x1 - 6 - k, 55 - k // 2, x1 - 6 - k, 55 - k // 2 + 1, accent_dark)
     # 通风槽（左下）
     for y in range(70, 100, 6):
         c.rect(x0 + 10, y, x0 + 50, y + 3, 'k')