fix: 修复配额说明重复和undefined问题

- 在editStorageForm中初始化oss_storage_quota_value和oss_quota_unit
- 删除重复的旧配额说明块，保留新的当前配额设置显示

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/routes/health.js

@@ -0,0 +1,52 @@
+/**
+ * 健康检查和公共配置路由
+ * 提供服务健康状态和公共配置信息
+ */
+
+const express = require('express');
+const router = express.Router();
+const { SettingsDB } = require('../database');
+
+/**
+ * 健康检查端点
+ * GET /api/health
+ */
+router.get('/health', (req, res) => {
+  res.json({ success: true, message: 'Server is running' });
+});
+
+/**
+ * 获取公开的系统配置（不需要登录）
+ * GET /api/config
+ */
+router.get('/config', (req, res) => {
+  const maxUploadSize = parseInt(SettingsDB.get('max_upload_size') || '10737418240');
+  res.json({
+    success: true,
+    config: {
+      max_upload_size: maxUploadSize
+    }
+  });
+});
+
+/**
+ * 获取公开的全局主题设置（不需要登录）
+ * GET /api/public/theme
+ */
+router.get('/public/theme', (req, res) => {
+  try {
+    const globalTheme = SettingsDB.get('global_theme') || 'dark';
+    res.json({
+      success: true,
+      theme: globalTheme
+    });
+  } catch (error) {
+    console.error('获取全局主题失败:', error);
+    res.status(500).json({
+      success: false,
+      message: '获取主题失败'
+    });
+  }
+});
+
+module.exports = router;