Problem

The Control UI sidebar nav currently renders a pinned set plus an expandable "MORE" section:

• The uppercase MORE header + chevron cost a row even when collapsed; expanded, the section (all unpinned routes, dynamic plugin tabs, and a dedicated "Edit pinned items" row) pushes the sessions list — the sidebar's main content — half off-screen.
• The expansion state is a persisted pref (sidebarMoreExpanded in ui/src/app/settings.ts), an extra settings surface that exists only to remember a chevron.
• "Edit pinned items" occupies a permanent nav row for a rarely used action.

Proposal

Replace the whole section with a single trailing "More" nav row that opens a transient popup menu (same pattern as Claude.ai's sidebar "More" item):

• Menu lists unpinned routes (click navigates) and dynamic plugin tabs, with a separator and an "Edit pinned items" entry that opens the existing pin-editor menu in place.
• The More row shows the active state when the current route lives inside the menu.
• Delete the expandable section, the MORE header/chevron, the dedicated edit row, and the sidebarMoreExpanded pref (transient UI state needs no migration).

Net effect: nav is always exactly pinned rows + one More row; sessions get the vertical space back; one less persisted setting.