feat: 重新设计底部tab身图标为弯曲胳膊

身(土)图标从臂肌改为弯曲胳膊造型，更直观展示手臂力量感。

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>