feat: 改进管理界面弹窗体验和滚动条美化

- 修复API Key创建/编辑弹窗和账户信息修改弹窗在低高度屏幕上被遮挡的问题
- 为所有弹窗添加自适应高度支持，最大高度限制为90vh
- 美化Claude账户弹窗的滚动条样式，使用紫蓝渐变色与主题保持一致
- 添加响应式适配，移动设备上弹窗高度调整为85vh
- 优化滚动条交互体验，支持悬停和激活状态

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

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

src/routes/web.js

@@ -217,7 +217,7 @@ router.post('/auth/change-password', async (req, res) => {
     
     try {
       const initData = JSON.parse(fs.readFileSync(initFilePath, 'utf8'));
-      const oldData = { ...initData }; // 备份旧数据
+      // const oldData = { ...initData }; // 备份旧数据
       
       // 更新 init.json
       initData.adminUsername = updatedUsername;
@@ -252,12 +252,12 @@ router.post('/auth/change-password', async (req, res) => {
     // 清除当前会话（强制用户重新登录）
     await redis.deleteSession(token);
 
-    logger.success(`🔐 Admin password changed successfully for user: ${updatedAdminData.username}`);
+    logger.success(`🔐 Admin password changed successfully for user: ${updatedUsername}`);
 
     res.json({
       success: true,
       message: 'Password changed successfully. Please login again.',
-      newUsername: updatedAdminData.username
+      newUsername: updatedUsername
     });
 
   } catch (error) {