feat: enhance v2 components and entity join functionality

- Add entity join controller/routes enhancements
- Improve table management and category value services
- Update v2 table list, card display, search widget components
- Improve split panel layout responsiveness

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/components/screen/InteractiveDataTable.tsx

@@ -648,24 +648,31 @@ export const InteractiveDataTable: React.FC<InteractiveDataTableProps> = ({
             );
 
             if (response.data.success && response.data.data) {
-              // valueCode 및 valueId -> {label, color} 매핑 생성
+              // valueCode 및 valueId -> {label, color} 매핑 생성 (트리 재귀 평탄화)
               const mapping: Record<string, { label: string; color?: string }> = {};
-              response.data.data.forEach((item: any) => {
-                // valueCode로 매핑
-                if (item.valueCode) {
-                  mapping[item.valueCode] = {
-                    label: item.valueLabel,
-                    color: item.color,
-                  };
-                }
-                // valueId로도 매핑 (숫자 ID 저장 시 라벨 표시용)
-                if (item.valueId !== undefined && item.valueId !== null) {
-                  mapping[String(item.valueId)] = {
-                    label: item.valueLabel,
-                    color: item.color,
-                  };
-                }
-              });
+              const flattenCategoryTree = (items: any[], parentLabel: string = "") => {
+                items.forEach((item: any) => {
+                  const displayLabel = parentLabel
+                    ? `${parentLabel} / ${item.valueLabel}`
+                    : item.valueLabel;
+                  if (item.valueCode) {
+                    mapping[item.valueCode] = {
+                      label: displayLabel,
+                      color: item.color,
+                    };
+                  }
+                  if (item.valueId !== undefined && item.valueId !== null) {
+                    mapping[String(item.valueId)] = {
+                      label: displayLabel,
+                      color: item.color,
+                    };
+                  }
+                  if (item.children && Array.isArray(item.children) && item.children.length > 0) {
+                    flattenCategoryTree(item.children, item.valueLabel);
+                  }
+                });
+              };
+              flattenCategoryTree(response.data.data);
               mappings[col.columnName] = mapping;
               console.log(`✅ 카테고리 매핑 로드 성공 [${col.columnName}]:`, mapping, { menuObjid });
             }