fix: 컬럼 리사이즈 중 텍스트 선택 방지

- 컬럼 헤더에 select-none, userSelect: 'none' 추가
- 드래그 중 document.body.userSelect = 'none'으로 전역 텍스트 선택 차단
- 드래그 완료 후 userSelect 복원
- 드래그 중 cursor를 col-resize로 고정하여 UX 개선

frontend/components/screen/InteractiveDataTable.tsx

@@ -1940,10 +1940,11 @@ export const InteractiveDataTable: React.FC<InteractiveDataTableProps> = ({
                         return (
                           <TableHead
                             key={column.id}
-                            className="relative bg-gradient-to-r from-gray-50 to-slate-50 px-4 font-semibold text-gray-700"
+                            className="relative bg-gradient-to-r from-gray-50 to-slate-50 px-4 font-semibold text-gray-700 select-none"
                             style={{ 
                               width: columnWidth ? `${columnWidth}px` : defaultWidth,
-                              minWidth: '80px'
+                              minWidth: '80px',
+                              userSelect: 'none'
                             }}
                           >
                             {column.label}
@@ -1956,13 +1957,22 @@ export const InteractiveDataTable: React.FC<InteractiveDataTableProps> = ({
                                   const startX = e.clientX;
                                   const startWidth = columnWidth || (e.currentTarget.parentElement?.offsetWidth || 100);
                                   
+                                  // 드래그 중 텍스트 선택 방지
+                                  document.body.style.userSelect = 'none';
+                                  document.body.style.cursor = 'col-resize';
+                                  
                                   const handleMouseMove = (moveEvent: MouseEvent) => {
+                                    moveEvent.preventDefault();
                                     const diff = moveEvent.clientX - startX;
                                     const newWidth = Math.max(80, startWidth + diff);
                                     setColumnWidths(prev => ({ ...prev, [column.id]: newWidth }));
                                   };
                                   
                                   const handleMouseUp = () => {
+                                    // 텍스트 선택 복원
+                                    document.body.style.userSelect = '';
+                                    document.body.style.cursor = '';
+                                    
                                     document.removeEventListener('mousemove', handleMouseMove);
                                     document.removeEventListener('mouseup', handleMouseUp);
                                   };