feat: 添加 README，更新 .gitignore，移除 JE-Skin/eskin-finger-sdk

- 添加 README.md 项目文档
- 更新 .gitignore 排除 JE-Skin/、eskin-finger-sdk/ 及构建产物
- 从 git 跟踪中移除 JE-Skin 和 eskin-finger-sdk

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/serial_core/serial.rs

@@ -93,4 +93,4 @@ impl ReadWrite for SerialPortReadWrite {
     fn write_all(&mut self, buf: &[u8]) -> std::io::Result<()> {
         self.inner.write_all(buf)
     }
-}
+}