refactor(workflow): 优化工作流引擎代码结构

- 将业务编号前缀定义为类级别常量，提高代码可维护性
- 统一使用类级别的prefix常量替换硬编码字符串
- 修复左连接查询中的参数命名格式，提升代码一致性
- 清理重复的前缀变量声明，减少代码冗余

OpenAuth.App/workflow/WorkflowEngineApp.cs

@@ -19,6 +19,8 @@ public class WorkflowEngineApp : SqlSugarBaseApp<SysCategoryType, SugarDbContext
 
     private readonly BusinessNoGenerator _businessNoGenerator;
 
+    private readonly string prefix = "wfjszl";
+
 
     public WorkflowEngineApp(ISugarUnitOfWork<SugarDbContext> unitWork, ISimpleClient<SysCategoryType> repository,
         IAuth auth, BusinessNoGenerator businessNoGenerator) : base(unitWork, repository, auth)
@@ -131,7 +133,6 @@ public class WorkflowEngineApp : SqlSugarBaseApp<SysCategoryType, SugarDbContext
             else
             {
                 // 取号
-                var prefix = "wfjszl";
                 var businessNo = _businessNoGenerator.GenerateBusinessNo(prefix);
 
                 requestDto.BusinessNo = businessNo;
@@ -1051,7 +1052,7 @@ public class WorkflowEngineApp : SqlSugarBaseApp<SysCategoryType, SugarDbContext
         {
             if (string.IsNullOrEmpty(requestDto.BusinessNo))
             {
-                var businessNo = _businessNoGenerator.GenerateBusinessNo("wf");
+                var businessNo = _businessNoGenerator.GenerateBusinessNo(prefix);
                 UnitWork.Db.Ado.BeginTran();
                 var user = _auth.GetCurrentUser().User;
                 var illegalConstructionAssessment = new IllegalConstructionAssessment
@@ -1173,10 +1174,10 @@ public class WorkflowEngineApp : SqlSugarBaseApp<SysCategoryType, SugarDbContext
             .Queryable<ZyFlowWorkitem>()
             .LeftJoin<ZyFlowParallelAudit>((w, a)
                 => w.InstanceId == a.InstanceId && w.HandlerId == a.AuditorId)
-            .LeftJoin<ZyFlowNode>((w,a,n)=>w.NodeId == n.NodeId)
+            .LeftJoin<ZyFlowNode>((w, a, n) => w.NodeId == n.NodeId)
             .Where(w => w.InstanceId == instance.InstanceId)
             .OrderByDescending(w => w.WorkitemId)
-            .Select((w, a,n) => new
+            .Select((w, a, n) => new
                 ZyFlowWorkitem
                 {
                     WorkitemId = w.WorkitemId,