feat: enhance split panel and tab component interactions

- Improved the drop handling logic for split panels and tabs, prioritizing the innermost container during drag-and-drop operations.
- Added internal state management for selected components within split panels to enhance user experience.
- Updated the rendering logic to ensure proper data attributes are set for design mode, facilitating better component identification.
- Enhanced the dynamic component rendering to support updates and selections for nested components within tabs and split panels.

Made-with: Cursor

frontend/lib/registry/components/v2-split-panel-layout/SplitPanelLayoutComponent.tsx

@@ -271,8 +271,9 @@ export const SplitPanelLayoutComponent: React.FC<SplitPanelLayoutComponentProps>
   const [dragPosition, setDragPosition] = useState<{ x: number; y: number } | null>(null);
   const [resizingCompId, setResizingCompId] = useState<string | null>(null);
   const [resizeSize, setResizeSize] = useState<{ width: number; height: number } | null>(null);
-  // 🆕 외부에서 전달받은 선택 상태 사용 (탭 컴포넌트와 동일 구조)
-  const selectedPanelComponentId = externalSelectedPanelComponentId || null;
+  // 내부 선택 상태 (외부 prop 없을 때 fallback)
+  const [internalSelectedCompId, setInternalSelectedCompId] = useState<string | null>(null);
+  const selectedPanelComponentId = externalSelectedPanelComponentId ?? internalSelectedCompId;
   // 🆕 커스텀 모드: 분할패널 내 탭 컴포넌트의 선택 상태 관리
   const [nestedTabSelectedCompId, setNestedTabSelectedCompId] = useState<string | undefined>(undefined);
   const rafRef = useRef<number | null>(null);
@@ -3052,9 +3053,15 @@ export const SplitPanelLayoutComponent: React.FC<SplitPanelLayoutComponentProps>
               </div>
             </div>
           )}
-          <CardContent className="flex-1 overflow-auto p-4">
+          <CardContent 
+            className="flex-1 overflow-auto p-4"
+            {...(isDesignMode ? {
+              "data-split-panel-container": "true",
+              "data-component-id": component.id,
+              "data-panel-side": "left",
+            } : {})}
+          >
             {/* 좌측 데이터 목록/테이블/커스텀 */}
-            {console.log("🔍 [SplitPanel] 왼쪽 패널 displayMode:", componentConfig.leftPanel?.displayMode, "isDesignMode:", isDesignMode)}
             {componentConfig.leftPanel?.displayMode === "custom" ? (
               // 🆕 커스텀 모드: 패널 안에 자유롭게 컴포넌트 배치
               <div 
@@ -3158,10 +3165,10 @@ export const SplitPanelLayoutComponent: React.FC<SplitPanelLayoutComponentProps>
                             }}
                             onClick={(e) => {
                               e.stopPropagation();
-                              // 패널 컴포넌트 선택 시 탭 내 선택 해제
                               if (comp.componentType !== "v2-tabs-widget") {
                                 setNestedTabSelectedCompId(undefined);
                               }
+                              setInternalSelectedCompId(comp.id);
                               onSelectPanelComponent?.("left", comp.id, comp);
                             }}
                           >
@@ -3917,7 +3924,14 @@ export const SplitPanelLayoutComponent: React.FC<SplitPanelLayoutComponentProps>
               </div>
             </div>
           )}
-          <CardContent className="flex-1 overflow-auto p-4">
+          <CardContent 
+            className="flex-1 overflow-auto p-4"
+            {...(isDesignMode ? {
+              "data-split-panel-container": "true",
+              "data-component-id": component.id,
+              "data-panel-side": "right",
+            } : {})}
+          >
             {/* 추가 탭 컨텐츠 */}
             {activeTabIndex > 0 ? (
               (() => {
@@ -4289,6 +4303,7 @@ export const SplitPanelLayoutComponent: React.FC<SplitPanelLayoutComponentProps>
                               if (comp.componentType !== "v2-tabs-widget") {
                                 setNestedTabSelectedCompId(undefined);
                               }
+                              setInternalSelectedCompId(comp.id);
                               onSelectPanelComponent?.("right", comp.id, comp);
                             }}
                           >