phsl / new-api

Adds a smoother mobile experience by automatically closing the sidebar
drawer once a menu item is tapped.

### Details
* SiderBar
  * Introduce `onNavigate` prop and invoke it on every `<Link>` click.
  * Remove unused `useIsMobile` hook and related `isMobile` variable.
* PageLayout
  * Pass `onNavigate` callback to `SiderBar` that sets `drawerOpen` to
    `false` when on mobile, ensuring the sidebar collapses after
    navigation.

This eliminates the “isMobile declared but never used” warning and
aligns the behaviour of the sidebar with common mobile UX expectations.