feat: showDate toggle on card via task modal checkbox

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/dashboard/TaskCard.tsx

@@ -125,6 +125,7 @@ export function TaskCard({
       issueNote:   data.issueNote || null,
       startDate:   data.startDate || null,
       dueDate:     data.dueDate || null,
+      showDate:    data.showDate,
       quarter:     data.quarter,
       priority:    'MEDIUM',
       creatorId:   'system',
@@ -144,6 +145,7 @@ export function TaskCard({
       issueNote:   data.issueNote || null,
       startDate:   data.startDate || null,
       dueDate:     data.dueDate || null,
+      showDate:    data.showDate,
     });
     setModalMode(null);
   };
@@ -192,7 +194,7 @@ export function TaskCard({
         {/* ── 기간 + 상태 ── */}
         <div className="mt-1 flex items-center gap-2">
           <span className="text-sm text-gray-400 font-medium flex-1 truncate">
-            {(task.startDate || task.dueDate)
+            {task.showDate && (task.startDate || task.dueDate)
               ? `${task.startDate ? fmtDate(task.startDate) : '?'} ~ ${task.dueDate ? fmtDate(task.dueDate) : '?'}`
               : ''}
           </span>