feat: 重构前端代码结构并添加Java后端支持

- 重构前端导入和组件结构，优化代码组织
- 添加Java后端基础框架和API实现
- 修复类型定义和接口兼容性问题
- 新增测试页面和工具函数
- 优化国际化支持和错误处理
- 更新依赖配置和构建脚本

新增Java后端模块：
- 实现基础认证、订单、支付等服务
- 添加Swagger API文档支持
- 配置数据库连接和缓存
- 实现国际化消息处理
- 添加安全过滤器和限流控制

serverjava/target/classes/i18n/messages.properties

@@ -0,0 +1,62 @@
+# Authentication messages
+auth.register.success=User registered successfully
+auth.login.success=Login successful
+auth.login.failure=Invalid username or password
+auth.username.required=Username is required
+auth.password.required=Password is required
+auth.email.required=Email is required
+auth.email.invalid=Invalid email format
+auth.password.minlength=Password must be at least 6 characters
+auth.username.minlength=Username must be at least 3 characters
+auth.username.exists=Username already exists
+
+# Product messages
+product.create.success=Product created successfully
+product.update.success=Product updated successfully
+product.delete.success=Product deleted successfully
+product.not.found=Product not found
+product.title.required=Product title is required
+product.price.required=Product price is required
+product.price.positive=Product price must be positive
+
+# Order messages
+order.create.success=Order created successfully
+order.update.success=Order updated successfully
+order.not.found=Order not found
+order.status.updated=Order status updated successfully
+
+# Payment messages
+payment.create.success=Payment created successfully
+payment.update.success=Payment updated successfully
+payment.not.found=Payment not found
+payment.status.updated=Payment status updated successfully
+
+# Logistics messages
+logistics.create.success=Logistics created successfully
+logistics.update.success=Logistics updated successfully
+logistics.not.found=Logistics not found
+logistics.status.updated=Logistics status updated successfully
+
+# Alert messages
+alert.create.success=Alert created successfully
+alert.update.success=Alert updated successfully
+alert.resolve.success=Alert resolved successfully
+alert.not.found=Alert not found
+
+# Monitoring messages
+monitoring.health.ok=System health is OK
+monitoring.health.error=System health check failed
+monitoring.metrics.success=Performance metrics retrieved successfully
+monitoring.services.success=Service status retrieved successfully
+monitoring.database.success=Database status retrieved successfully
+monitoring.cache.success=Cache status retrieved successfully
+monitoring.stats.success=System stats retrieved successfully
+
+# Common messages
+common.success=Operation successful
+common.error=Operation failed
+common.invalid.request=Invalid request
+common.missing.parameter=Missing required parameter
+common.not.found=Resource not found
+common.access.denied=Access denied
+common.server.error=Server internal error