phsl / new-api

- Hide scrollbars for .semi-layout, .semi-layout-content, and .semi-sider
- Set scrollbar width and height to 0 for webkit browsers
- Add cross-browser scrollbar hiding support (webkit, firefox, IE/Edge)
- Change Content container overflow from 'auto' to 'hidden' on desktop
- Remove redundant scrollbar styling (thumb, hover, track styles)

This ensures that all semi-layout related components have no visible
scrollbars and prevents vertical scrolling functionality entirely.

Files modified:
- web/src/index.css
- web/src/components/layout/PageLayout.js