Fullscreen API

[xiaotiandada]

• https://developer.mozilla.org/en-US/docs/Web/API/Fullscreen_API
• https://github.com/rafgraph/fscreen/blob/main/src/fscreen.js
• https://web.dev/native-hardware-fullscreen/#let-the-user-choose-when-to-go-fullscreen

全屏 IOS 不支持，可以通过 CSS Fixed + PWA 实现比较好的体验