feat: ComfyUI 默认提示词统一改为「填充遮罩区域的头发，人物增加一点磨皮」

- app.py 各接口 Form 默认值与说明、hairline/service.py _REDRAW_PROMPT、
  hairline/redraw.py _DEFAULT_PROMPT、face_analysis/hairline_grow.py 兜底值
- add_hair.json / add_hair2.json / 0716add-hair-api.json / 0716add-hair.json /
  hair_repaint.json 工作流节点60内置文本
- static 测试页、local_test、benchmark 脚本、接口文档同步
注意：新提示词首次请求会因 CLIP 缓存失效变慢一次，之后恢复

tests/test_reqlog.py

@@ -37,7 +37,7 @@ def test_extract_scalars_and_images(tmp_path):
     b64 = "data:image/png;base64," + base64.b64encode(_PNG).decode()
     body = _multipart(
         fields={"gender": "female", "hair_style": "1,3", "use_mask": "True",
-                "prompt": "填充遮罩区域的头发", "image_base64": b64},
+                "prompt": "填充遮罩区域的头发，人物增加一点磨皮", "image_base64": b64},
         files={"image_file": ("x.png", "image/png", _PNG)},
     )
     ct = "multipart/form-data; boundary=----testbnd"