fix: Collapsible 레이아웃 구조 수정

- CardContent 내부에서 CollapsibleContent가 제대로 렌더링되도록 구조 수정
- mb-2, mt-2로 간격 조정
- 오른쪽으로 밀려나는 문제 해결

frontend/lib/registry/components/selected-items-detail-input/SelectedItemsDetailInputConfigPanel.tsx

@@ -637,8 +637,8 @@ export const SelectedItemsDetailInputConfigPanel: React.FC<SelectedItemsDetailIn
             onOpenChange={(open) => setExpandedGroups(prev => ({ ...prev, [group.id]: open }))}
           >
             <Card className="border-2">
-              <CardContent className="space-y-2 p-3 sm:space-y-3 sm:p-4">
-                <div className="flex items-center justify-between">
+              <CardContent className="p-3 sm:p-4">
+                <div className="flex items-center justify-between mb-2">
                   <CollapsibleTrigger asChild>
                     <Button variant="ghost" size="sm" className="h-auto p-0 hover:bg-transparent">
                       <div className="flex items-center gap-2">
@@ -664,7 +664,7 @@ export const SelectedItemsDetailInputConfigPanel: React.FC<SelectedItemsDetailIn
                   </Button>
                 </div>
 
-                <CollapsibleContent className="space-y-2 sm:space-y-3">
+                <CollapsibleContent className="space-y-2 sm:space-y-3 mt-2">
                   {/* 그룹 ID */}
               <div className="space-y-1">
                 <Label className="text-[10px] sm:text-xs">그룹 ID</Label>
@@ -894,10 +894,9 @@ export const SelectedItemsDetailInputConfigPanel: React.FC<SelectedItemsDetailIn
                     ))}
                   </div>
                   )}
-                </CollapsibleContent>
-                </div>
-              </Collapsible>
-
+                  </CollapsibleContent>
+                  </div>
+                </Collapsible>
                 </CollapsibleContent>
               </CardContent>
             </Card>