In the mobile drawer the nav's flex-1 filled the full-height panel, pushing
the WorkspaceSwitcher to the very bottom and leaving a large empty void between
the menu and the switcher. Add a 'grow' prop to SidebarNav (default true =
desktop bottom-anchor) and pass grow=false in the mobile drawer so the nav
takes only its natural height — logo, menu and switcher group together at the
top. Desktop sidebar unchanged. +2 Vitest assertions for the contract.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>