fix: 修复Docker构建和路径解析问题

- 在Dockerfile中使用npm中国镜像加速依赖安装
- 修正后端健康检查端点路径
- 修复Docker环境中图片路径解析问题
- 修正前端API地址默认值

frontend/Dockerfile

@@ -8,8 +8,9 @@ WORKDIR /app
 # Copy package files
 COPY package*.json ./
 
-# Install dependencies
-RUN npm ci
+# Install dependencies with Chinese mirror
+RUN npm config set registry https://registry.npmmirror.com && \
+    npm ci
 
 # ========================================
 # Stage 2: Builder

frontend/src/pages/SettingsPage.tsx

@@ -6,7 +6,7 @@ import { Settings, Save, CheckCircle, XCircle, Eye, EyeOff, Server, Globe, Datab
 
 // 从环境变量或 localStorage 获取 API 地址
 const getDefaultApiUrl = () => {
-  return import.meta.env.VITE_API_URL || localStorage.getItem('api_base_url') || '/';
+  return import.meta.env.VITE_API_URL || localStorage.getItem('api_base_url') || '';
 };
 
 type ApiConfig = {