위젯 커스텀 제목 및 헤더 표시/숨김 기능 추가

- 위젯 설정에서 제목 변경 가능
- 위젯 헤더 표시/숨김 토글 추가
- DB 마이그레이션 자동 실행 (custom_title, show_header 컬럼)
- 편집 모드/보기 모드 모두 지원
- DashboardTopMenu 레이아웃 유지

frontend/components/dashboard/DashboardViewer.tsx

@@ -280,29 +280,31 @@ function ViewerElement({ element, data, isLoading, onRefresh }: ViewerElementPro
       onMouseEnter={() => setIsHovered(true)}
       onMouseLeave={() => setIsHovered(false)}
     >
-      {/* 헤더 */}
-      <div className="flex items-center justify-between border-b border-gray-200 bg-gray-50 px-4 py-3">
-        <h3 className="text-sm font-semibold text-gray-800">{element.title}</h3>
+      {/* 헤더 (showHeader가 false가 아닐 때만 표시) */}
+      {element.showHeader !== false && (
+        <div className="flex items-center justify-between border-b border-gray-200 bg-gray-50 px-4 py-3">
+          <h3 className="text-sm font-semibold text-gray-800">{element.customTitle || element.title}</h3>
 
-        {/* 새로고침 버튼 (호버 시에만 표시) */}
-        {isHovered && (
-          <button
-            onClick={onRefresh}
-            disabled={isLoading}
-            className="hover:text-muted-foreground text-gray-400 disabled:opacity-50"
-            title="새로고침"
-          >
-            {isLoading ? (
-              <div className="h-4 w-4 animate-spin rounded-full border border-gray-400 border-t-transparent" />
-            ) : (
-              "🔄"
-            )}
-          </button>
-        )}
-      </div>
+          {/* 새로고침 버튼 (호버 시에만 표시) */}
+          {isHovered && (
+            <button
+              onClick={onRefresh}
+              disabled={isLoading}
+              className="hover:text-muted-foreground text-gray-400 disabled:opacity-50"
+              title="새로고침"
+            >
+              {isLoading ? (
+                <div className="h-4 w-4 animate-spin rounded-full border border-gray-400 border-t-transparent" />
+              ) : (
+                "🔄"
+              )}
+            </button>
+          )}
+        </div>
+      )}
 
       {/* 내용 */}
-      <div className="h-[calc(100%-57px)]">
+      <div className={element.showHeader !== false ? "h-[calc(100%-57px)]" : "h-full"}>
         {element.type === "chart" ? (
           <ChartRenderer element={element} data={data} width={element.size.width} height={element.size.height - 57} />
         ) : (