ui(editor): taskList 체크박스 커스텀 스타일

기본 OS 체크박스 외형 대신 primary 배경 + 흰색 체크 SVG로 일관된 톤 제공.

Author: teriusu-ko

src/styles/editor.css

@@ -124,11 +124,41 @@
 }
 
 .tiptap ul[data-type="taskList"] li > label input[type="checkbox"] {
-  accent-color: var(--primary);
+  appearance: none;
+  -webkit-appearance: none;
   width: 1.1em;
   height: 1.1em;
-  cursor: pointer;
   margin: 0;
+  padding: 0;
+  cursor: pointer;
+  background-color: var(--background, white);
+  border: 1.5px solid var(--border);
+  border-radius: 4px;
+  transition:
+    background-color 0.12s ease,
+    border-color 0.12s ease,
+    box-shadow 0.12s ease;
+  display: inline-block;
+  vertical-align: middle;
+  flex-shrink: 0;
+}
+
+.tiptap ul[data-type="taskList"] li > label input[type="checkbox"]:hover {
+  border-color: var(--muted-foreground);
+}
+
+.tiptap ul[data-type="taskList"] li > label input[type="checkbox"]:focus-visible {
+  outline: none;
+  box-shadow: 0 0 0 2px var(--background, white), 0 0 0 4px var(--primary);
+}
+
+.tiptap ul[data-type="taskList"] li > label input[type="checkbox"]:checked {
+  background-color: var(--primary);
+  border-color: var(--primary);
+  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='none' stroke='white' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='3.5 8.5 6.5 11.5 12.5 5'/%3E%3C/svg%3E");
+  background-repeat: no-repeat;
+  background-position: center;
+  background-size: 100% 100%;
 }
 
 .tiptap ul[data-type="taskList"] li > div {