feat: 新增工作流执行模块

新增流程执行记录的实体、DTO、DAO、控制器和服务层，支持工作流的执行、回调及结果树状列表查询；同时更新服务名称为 ai-agent。

workflow/consts/node/node_execution_status.go

@@ -0,0 +1,29 @@
+package node
+
+import "github.com/gogf/gf/v2/util/gconv"
+
+var (
+	NodeExecutionStatusRunning = newNodeExecutionStatus(gconv.PtrInt8(1), "running") // 运行中
+	NodeExecutionStatusSuccess = newNodeExecutionStatus(gconv.PtrInt8(2), "success") // 成功
+	NodeExecutionStatusFailed  = newNodeExecutionStatus(gconv.PtrInt8(3), "failed")  // 失败
+	NodeExecutionStatusPaused  = newNodeExecutionStatus(gconv.PtrInt8(4), "paused")  // 暂停
+	NodeExecutionStatusWait    = newNodeExecutionStatus(gconv.PtrInt8(5), "wait")    // 等待执行
+)
+
+type NodeExecutionStatus *int8
+
+type nodeExecutionStatus struct {
+	code NodeExecutionStatus
+	desc string
+}
+
+func (s nodeExecutionStatus) Code() NodeExecutionStatus {
+	return s.code
+}
+func (s nodeExecutionStatus) Desc() string {
+	return s.desc
+}
+
+func newNodeExecutionStatus(code NodeExecutionStatus, desc string) nodeExecutionStatus {
+	return nodeExecutionStatus{code: code, desc: desc}
+}