feat(logo): 应用图标改为印泥铺满，不留白边

- build_logo.py 新增 svg/app-icon.svg：印章实心部分撑满画布，毛边外的空隙用印章红补齐，白字和颗粒保留
- build_assets.sh 由 app-icon.svg 渲染 180 / 192 / 512 / 1024px 图标，方形、不带透明，圆角交给系统
- logo-spec.md 同步资产清单

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

docs/design/logo/scripts/build_logo.py

@@ -3,7 +3,7 @@
 用法：.work/venv/bin/python scripts/build_logo.py
 通常由 scripts/build_assets.sh 调用；运行前 svg/ 里要已有 seal*.svg。
 """
-from logo_lib import FINAL, FINAL_INSET, LOGO, NAVY, WHITE, lockup_h2, lockup_vertical, wordmark
+from logo_lib import FINAL, FINAL_INSET, LOGO, NAVY, SEAL_RED, WHITE, lockup_h2, lockup_vertical, seal_group, wordmark
 
 SVG = LOGO / "svg"
 
@@ -31,4 +31,10 @@ for color, name in (("#000000", "logo-mono-black.svg"), ("#FFFFFF", "logo-mono-w
     body, w, h = wordmark(FINAL, color, inset=FINAL_INSET)
     write(name, lockup_h2(body, w, h, kind="clean", seal_color=color))
 
-print("ok", sorted(p.name for p in SVG.glob("logo-*.svg")) + ["wordmark.svg", "wordmark-reverse.svg"])
+# 应用图标：印泥铺满，不留白边。印章实心部分撑满画布，毛边外的空隙用印章红补齐；
+# 印章下面垫纸色底，白字和颗粒仍显示为白色
+seal, _ = seal_group("textured", 0, 0, 100, on_dark=True)
+write("app-icon.svg", f'<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">'
+                      f'<rect width="100" height="100" fill="{SEAL_RED}"/>{seal}</svg>')
+
+print("ok", sorted(p.name for p in SVG.glob("logo-*.svg")) + ["wordmark.svg", "wordmark-reverse.svg", "app-icon.svg"])