feat(webapp) add setting page

[huanghuang358]

Close #19 .

1. Add setting button at both Welcome and Devicebar.

Welcome	DeviceBar

2. Apply responsive design based on md: lg: 2xl: provided by unocss .
3. Share screen button is disabled on mobile devices even though it is not hidden.
4. More details can be found at the setting page.

[rocka]

Generally looks fine, better if remembered DRY (Don't Repeat Yourself)

[rocka]

Those setting values made me think that maybe we should switch to some centerialized store library, like https://github.com/pmndrs/zustand

Instead of passing onChangedDeviceVideo into the <Settings /> component, we read the store value by useStore and react on value changes by useEffect. Also it's more easy to save/restore the setting values to/from localStorage as a hole.

[huanghuang358]

I think now all issues are resolved. Is there anything I can improve?