fix(packages/ui): hide navbar divider when no items render to its right

[zrosenbauer]

Summary

The navbar renders a vertical separator (NavMenuDivider) unconditionally inside the rp-nav__others container, even when no items (social links, dark/light toggle, language switcher, version switcher) are visible to its right.

Current behavior

In the upstream Rspress Nav component (@rspress/core — eject-theme/components/Nav/index.tsx:49-55), the divider is always rendered:

<div className="rp-nav__others">
  <NavMenuDivider />
  <NavLangs />
  <NavVersions />
  {hasAppearanceSwitch && <SwitchAppearance />}
  <SocialLinks />
</div>

When a zpress consumer disables social links, dark mode, langs, and versions, the .rp-nav-menu__divider 1px vertical line still appears with nothing beside it.

Expected behavior

The divider should not be visible when there are no sibling elements rendering content to its right.

Location

• @rspress/core eject-theme/components/Nav/index.tsx ~line 50 — unconditional <NavMenuDivider />
• @rspress/core eject-theme/components/Nav/NavMenu.css ~line 69 — .rp-nav-menu__divider styles
• packages/ui/src/theme/components/nav/layout.tsx — zpress Layout wrapper

Proposed approach

Override via CSS in the zpress theme: use :has() to hide .rp-nav-menu__divider when it is the only visible child of .rp-nav__others, e.g.:

.rp-nav__others:not(:has(.rp-nav-menu__divider ~ *:not(:empty))) .rp-nav-menu__divider {
  display: none;
}

Or eject/override the Nav component to conditionally render the divider.