fix(desktop): let the pinned sidebar section grow to fit all pins

The pinned list was hard-capped at max-h-44 with an invisible scrollbar;
cap it at half the viewport instead so every pin is visible.

apps/desktop/src/app/chat/sidebar/index.tsx

@@ -1239,7 +1239,7 @@ export function ChatSidebar({
             {!trimmedQuery && (
               <SidebarSessionsSection
                 activeSessionId={activeSidebarSessionId}
-                contentClassName={cn('flex max-h-44 flex-col gap-px rounded-lg pb-2 pt-1', GROUP_BODY)}
+                contentClassName={cn('flex max-h-[50vh] flex-col gap-px rounded-lg pb-2 pt-1', GROUP_BODY)}
                 dndSensors={dndSensors}
                 emptyState={<SidebarPinnedEmptyState />}
                 label={s.pinned}