🐛 修复文件列表hover时变白的问题

- 移除硬编码的mouseover/mouseout颜色
- 添加.file-list-row类使用CSS处理hover效果
- 深色/浅色主题都使用半透明紫色作为hover背景

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/app.html

@@ -925,6 +925,19 @@
       color: var(--text-secondary);
     }
 
+    /* 文件列表行样式 */
+    .file-list-row {
+      border-bottom: 1px solid var(--glass-border);
+      cursor: pointer;
+      transition: background 0.15s ease;
+    }
+    .file-list-row:hover {
+      background: rgba(102, 126, 234, 0.08);
+    }
+    body.light-theme .file-list-row:hover {
+      background: rgba(102, 126, 234, 0.06);
+    }
+
     /* ========== 危险按钮 ========== */
     .btn-danger {
       background: linear-gradient(135deg, #ef4444, #dc2626);
@@ -1390,14 +1403,12 @@
               </thead>
               <tbody>
                 <tr v-for="file in files" :key="file.name"
-                    style="border-bottom: 1px solid #eee; cursor: pointer;"
+                    class="file-list-row"
                     @click="handleFileClick(file)"
                     @contextmenu.prevent="showFileContextMenu(file, $event)"
                     @touchstart="handleLongPressStart(file, $event)"
                     @touchmove="handleLongPressMove($event)"
-                    @touchend="handleLongPressEnd"
-                    @mouseover="$event.currentTarget.style.background='#f9f9f9'"
-                    @mouseout="$event.currentTarget.style.background='white'">
+                    @touchend="handleLongPressEnd">
                   <td style="padding: 10px;">
                     <div style="display: flex; align-items: center; gap: 10px; overflow: hidden;">
                     <!-- 图片缩略图 -->