fix(terminal): make worktree dropdown scrollable and show all items

Replace Radix ScrollArea with a plain overflow-y-auto div and increase
max height from 300px to min(500px, 60vh). The Radix ScrollArea wasn't
scrolling properly, causing task worktrees (209, 210, 211) to be hidden
below the fold with no visible scrollbar on macOS.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/frontend/src/renderer/components/terminal/WorktreeSelector.tsx

@@ -17,7 +17,6 @@ import {
   AlertDialogHeader,
   AlertDialogTitle,
 } from '../ui/alert-dialog';
-import { ScrollArea } from '../ui/scroll-area';
 import { cn } from '../../lib/utils';
 import { useProjectStore } from '../../stores/project-store';
 
@@ -459,7 +458,7 @@ export function WorktreeSelector({
         <div className="border-t border-border" />
 
         {/* Scrollable results */}
-        <ScrollArea className="max-h-[300px]">
+        <div className="max-h-[min(500px,60vh)] overflow-y-auto">
           <div id={listboxId} role="listbox" aria-label={t('terminal:worktree.searchPlaceholder')} className="p-1">
             {isLoading ? (
               <div className="flex items-center justify-center py-2">
@@ -507,7 +506,7 @@ export function WorktreeSelector({
               </>
             )}
           </div>
-        </ScrollArea>
+        </div>
       </PopoverContent>
     </Popover>