fix: 支持编辑分类

- 分类项添加编辑按钮
- 悬停时显示编辑按钮
- 点击编辑按钮打开编辑弹窗

frontend/src/App.jsx

@@ -144,11 +144,16 @@ function App() {
           </div>
 
           {categories.map(cat => (
-            <div key={cat.id} className={`category-item ${selectedCategory === cat.id ? 'active' : ''}`} onClick={() => setSelectedCategory(cat.id)}>
+            <div key={cat.id} className="category-item-wrapper">
+              <div className={`category-item ${selectedCategory === cat.id ? 'active' : ''}`} onClick={() => setSelectedCategory(cat.id)}>
                 <div className="category-icon"><Icon name={cat.icon || 'folder'} size={14}/></div>
                 <span className="category-name">{cat.name}</span>
                 <span className="category-count">{getCategoryCount(cat.id)}</span>
               </div>
+              <button className="category-edit-btn" onClick={(e) => { e.stopPropagation(); openModal('category', cat) }} title="编辑">
+                <Icon name="edit" size={12}/>
+              </button>
+            </div>
           ))}
         </div>
 

frontend/src/index.css

@@ -88,6 +88,8 @@ body {
   margin-bottom: 4px;
   color: #666;
   font-size: 13px;
+  flex: 1;
+  min-width: 0;
 }
 
 .category-item:hover {
@@ -110,6 +112,7 @@ body {
   border-radius: 6px;
   background: rgba(0, 0, 0, 0.04);
   font-size: 14px;
+  flex-shrink: 0;
 }
 
 .category-item.active .category-icon {
@@ -128,12 +131,44 @@ body {
   padding: 2px 6px;
   background: rgba(0, 0, 0, 0.06);
   border-radius: 10px;
+  flex-shrink: 0;
 }
 
 .category-item.active .category-count {
   background: rgba(255, 255, 255, 0.2);
 }
 
+.category-item-wrapper {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+}
+
+.category-edit-btn {
+  width: 24px;
+  height: 24px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  border: none;
+  background: transparent;
+  color: #999;
+  cursor: pointer;
+  border-radius: 4px;
+  opacity: 0;
+  transition: all 0.2s ease;
+  flex-shrink: 0;
+}
+
+.category-item-wrapper:hover .category-edit-btn {
+  opacity: 1;
+}
+
+.category-edit-btn:hover {
+  background: rgba(102, 126, 234, 0.1);
+  color: #667eea;
+}
+
 /* 侧边栏底部 */
 .sidebar-footer {
   padding: 16px;