feat: 工单执行人直接执行(自动通过) + 审批时间线 + 执行结果展示

后端:
- 创建工单时检测是否有审核步骤，无审核步骤直接设为 reviewing
- ExecuteTicket 允许 reviewing 状态，自动通过 execute 审批记录再执行
- 验证执行人权限（非执行人返回 403）
- 列表 API 返回 has_audit_step/is_executor/is_approver 元信息
- 详情 API 返回 approvals 带 approver_name/actual_approver_name

前端:
- 按钮权限精确化：通过/拒绝只对审核人显示，执行只对执行人显示
- 详情弹框加载完整审批数据，展示操作时间线
- 时间线：提交人→每个步骤的指派人+实际操作人+操作时间+备注
- 执行结果文本格式 fallback 显示
- 失败工单显示失败原因

backend/internal/handler/ticket.go

@@ -101,9 +101,34 @@ func ListTickets(c *gin.Context) {
 	
 	var tickets []model.Ticket
 	query.Offset((page - 1) * limit).Limit(limit).Find(&tickets)
-	
+
+	// Enrich tickets with has_audit_step info
+	type TicketWithMeta struct {
+		model.Ticket
+		HasAuditStep    bool `json:"has_audit_step"`
+		HasExecuteStep  bool `json:"has_execute_step"`
+		IsExecutor      bool `json:"is_executor"`
+		IsApprover      bool `json:"is_approver"`
+	}
+	var result []TicketWithMeta
+	for _, t := range tickets {
+		var auditCount, execCount int64
+		model.DB.Model(&model.TicketApproval{}).Where("ticket_id = ? AND step_type = 'audit'", t.ID).Count(&auditCount)
+		model.DB.Model(&model.TicketApproval{}).Where("ticket_id = ? AND step_type = 'execute'", t.ID).Count(&execCount)
+		var isExec, isAppr int64
+		model.DB.Model(&model.TicketApproval{}).Where("ticket_id = ? AND step_type = 'execute' AND approver_id = ?", t.ID, userID).Count(&isExec)
+		model.DB.Model(&model.TicketApproval{}).Where("ticket_id = ? AND step_type != 'execute' AND step_type != 'submit' AND approver_id = ?", t.ID, userID).Count(&isAppr)
+		result = append(result, TicketWithMeta{
+			Ticket:         t,
+			HasAuditStep:   auditCount > 0,
+			HasExecuteStep: execCount > 0,
+			IsExecutor:     isExec > 0,
+			IsApprover:     isAppr > 0,
+		})
+	}
+
 	c.JSON(http.StatusOK, gin.H{
-		"items": tickets,
+		"items": result,
 		"total": total,
 		"page":  page,
 		"page_size": limit,
@@ -119,9 +144,31 @@ func GetTicket(c *gin.Context) {
 		return
 	}
 	
-	// Get approvals
+	// Get approvals — enrich with user display names
 	var approvals []model.TicketApproval
-	model.DB.Where("ticket_id = ?", id).Order("step_number").Find(&approvals)
+	model.DB.Where("ticket_id = ?", id).Order("step_number, id").Find(&approvals)
+	type ApprovalWithNames struct {
+		model.TicketApproval
+		ApproverName       string `json:"approver_name"`
+		ActualApproverName string `json:"actual_approver_name"`
+	}
+	var approvalsResult []ApprovalWithNames
+	for _, a := range approvals {
+		item := ApprovalWithNames{TicketApproval: a}
+		if a.ApproverID != nil {
+			var u model.User
+			if model.DB.First(&u, *a.ApproverID).Error == nil {
+				item.ApproverName = u.DisplayName
+			}
+		}
+		if a.ActualApproverID != nil {
+			var u model.User
+			if model.DB.First(&u, *a.ActualApproverID).Error == nil {
+				item.ActualApproverName = u.DisplayName
+			}
+		}
+		approvalsResult = append(approvalsResult, item)
+	}
 	
 	// Get SQL items
 	var sqlItems []model.TicketSQLItem
@@ -132,7 +179,7 @@ func GetTicket(c *gin.Context) {
 	// Marshal ticket to JSON then unmarshal to map for flattening
 	ticketBytes, _ := json.Marshal(ticket)
 	json.Unmarshal(ticketBytes, &result)
-	result["approvals"] = approvals
+	result["approvals"] = approvalsResult
 	result["sql_items"] = sqlItems
 	
 	// Add applicant_name and instance_name for frontend
@@ -213,6 +260,7 @@ func CreateTicket(c *gin.Context) {
 	}
 	
 	// Create approval records based on workflow or default to admin
+	hasAuditStep := false
 	if input.WorkflowID != nil && *input.WorkflowID > 0 {
 		// Load workflow steps
 		var wfSteps []model.WorkflowStep
@@ -221,6 +269,9 @@ func CreateTicket(c *gin.Context) {
 			if ws.StepType == "submit" {
 				continue // submit step needs no approver
 			}
+			if ws.StepType != "execute" {
+				hasAuditStep = true
+			}
 			// Parse approver_ids from JSON
 			var approverIDs []int
 			if ws.ApproverIDs != nil && *ws.ApproverIDs != "" {
@@ -283,7 +334,14 @@ func CreateTicket(c *gin.Context) {
 			model.DB.Create(&approval)
 		}
 	}
-	
+
+	// If workflow has no audit step (only submit + execute), skip to reviewing
+	if !hasAuditStep {
+		reviewing := "reviewing"
+		model.DB.Model(&ticket).Update("status", reviewing)
+		ticket.Status = &reviewing
+	}
+
 	c.JSON(http.StatusCreated, ticket)
 }
 
@@ -369,11 +427,57 @@ func ExecuteTicket(c *gin.Context) {
 		return
 	}
 	
-	// Check ticket status
-	if ticket.Status != nil && *ticket.Status != "approved" {
+	// Check ticket status — allow approved OR reviewing (will auto-approve execute step)
+	if ticket.Status != nil && *ticket.Status != "approved" && *ticket.Status != "reviewing" {
 		c.JSON(http.StatusBadRequest, gin.H{"detail": "Ticket must be approved before execution"})
 		return
 	}
+
+	// Auto-approve any pending execute-type approval for the current user
+	userID, _, _ := middleware.GetCurrentUser(c)
+
+	// Verify current user is an executor for this ticket
+	var executorCheck int64
+	model.DB.Model(&model.TicketApproval{}).
+		Where("ticket_id = ? AND step_type = 'execute' AND (approver_id = ? OR approver_id IS NULL)", id, userID).
+		Count(&executorCheck)
+	if executorCheck == 0 {
+		c.JSON(http.StatusForbidden, gin.H{"detail": "你不是此工单的执行人"})
+		return
+	}
+
+	var pendingExec model.TicketApproval
+	if err := model.DB.Where("ticket_id = ? AND step_type = 'execute' AND action IS NULL", id).First(&pendingExec).Error; err == nil {
+		// Auto-approve the execute step
+		now := time.Now()
+		action := "approve"
+		comment := "自动通过（执行触发）"
+		pendingExec.Action = &action
+		pendingExec.Comment = &comment
+		pendingExec.ActualApproverID = &userID
+		pendingExec.CompletedAt = &now
+		model.DB.Save(&pendingExec)
+	}
+
+	// Check if all audit steps are approved
+	var pendingAudit int64
+	model.DB.Model(&model.TicketApproval{}).
+		Where("ticket_id = ? AND step_type = 'audit' AND action IS NULL", id).
+		Count(&pendingAudit)
+	if pendingAudit > 0 {
+		c.JSON(http.StatusBadRequest, gin.H{"detail": "还有未完成的审核步骤"})
+		return
+	}
+
+	// Check for rejected audit steps
+	var rejectedAudit int64
+	model.DB.Model(&model.TicketApproval{}).
+		Where("ticket_id = ? AND step_type = 'audit' AND action = 'reject'", id).
+		Count(&rejectedAudit)
+	if rejectedAudit > 0 {
+		c.JSON(http.StatusBadRequest, gin.H{"detail": "审核已被拒绝，无法执行"})
+		return
+	}
 	
 	// Get instance info
 	var instance model.Instance