- 新增实体类: SysApprovalFlow, SysApprovalRecord, SysApprovalHistory - 新增Repositories: ApprovalFlowRepository, ApprovalRecordRepository, ApprovalHistoryRepository - 完整实现ApprovalFlowService: 提交审批、处理审批、取消审批等 - 更新ApprovalController连接实际服务 - 添加单元测试ApprovalFlowServiceTest - 更新Ralph状态文件 (Phase 3: 90%)