파일 삭제 기능 추가, undo / redo 기능에 적용

src/renderer/style.css

@@ -307,6 +307,19 @@ main {
 }
 .card.selected .card-check { opacity: 1; }
 
+.card-delete {
+  position: absolute; top: 8px; right: 8px;
+  width: 22px; height: 22px; border-radius: 50%; border: none;
+  background: rgba(200, 40, 40, 0.88); color: #fff;
+  font-size: 16px; line-height: 1;
+  display: flex; align-items: center; justify-content: center;
+  cursor: pointer; padding: 0;
+  opacity: 0; transition: opacity .15s, transform .1s;
+  z-index: 3;
+}
+.card:hover .card-delete { opacity: 1; }
+.card-delete:hover { background: rgb(210, 30, 30); transform: scale(1.12); }
+
 .card-name {
   font-size: 11px; color: var(--muted);
   font-family: 'JetBrains Mono', monospace;