refactor: move config dir to ~/.config/hy3d, replace skill with run-hy3d

- config dir renamed hunyuan3dweb -> hy3d (cookies/profile moved intact,
  auth re-verified: quota 20/20)
- cli.py/login.py/READMEs/doc paths updated to ~/.config/hy3d
- skill: delete run-hunyuan3dweb, add run-hy3d pointing at bin/hy3d
- zero stale old-name references remain (one historical note in skill)

README_REVERSE_ENGINEERING_CN.md

@@ -90,8 +90,8 @@ resource_url = upload_image("/path/to/image.png")
 ```bash
 hy3d-login
 # 按提示输入邮箱和验证码
-# 登录状态自动保存到 ~/.config/hunyuan3dweb/profile
-# Cookie 同时导出到 ~/.config/hunyuan3dweb/cookies.txt
+# 登录状态自动保存到 ~/.config/hy3d/profile
+# Cookie 同时导出到 ~/.config/hy3d/cookies.txt
 ```
 
 **登录状态检测逻辑**（双重验证）：
@@ -104,7 +104,7 @@ hy3d-login
 ```python
 from hy3d import Hunyuan3DAPI
 
-# 自动从 ~/.config/hunyuan3dweb/cookies.txt 加载 cookie
+# 自动从 ~/.config/hy3d/cookies.txt 加载 cookie
 api = Hunyuan3DAPI()
 
 # 查询配额