[CLAUDE] App: Contract workflow inner steps DTO + designer mirror PE (Chunk B)

DTO + Validator + Handler mở rộng cho N-stage admin designer Contract
(Mig 20). Mirror PE Mig 18 pattern (PeWorkflowAdminFeatures Chunk B).

WorkflowAdminFeatures:
- WorkflowStepInnerStepDto record (Id, Order, DeptId, DeptName,
  PositionLevel, Name, SlaDays, IsRequired)
- WorkflowStepDto extend +InnerSteps List
- GetWorkflowAdminOverviewQueryHandler — Include InnerSteps OrderBy +
  resolve DeptNames cho display
- CreateWorkflowStepInnerStepInput record
- CreateWorkflowStepInput extend +InnerSteps (nullable, default null —
  backward compat existing test code positional new())
- Validator child rules cho InnerSteps (Order ≥1, DeptId not empty,
  PositionLevel 1-3, SlaDays ≥0)
- CreateWorkflowDefinitionCommandHandler — convert InnerSteps khi build
  entity (atomic batch insert qua nav collection)

Verify: dotnet build 0 error, 89 test pass (no regression).

Pending Chunk C: ContractWorkflowService.TransitionAsync N-stage logic
+ legacy 2-stage fallback mirror PE pattern.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Backend/SolutionErp.Application/Contracts/WorkflowAdminFeatures.cs

@@ -17,6 +17,17 @@ public record WorkflowStepApproverDto(
     string AssignmentValue,
     string? DisplayName);   // resolved role label or user fullName
 
+// Mig 20 — N-stage approval inner step level con (mirror PE Mig 18)
+public record WorkflowStepInnerStepDto(
+    Guid Id,
+    int Order,
+    Guid DepartmentId,
+    string? DepartmentName,
+    int PositionLevel,        // 1=NV, 2=PP, 3=TP
+    string? Name,
+    int? SlaDays,
+    bool IsRequired);
+
 public record WorkflowStepDto(
     Guid Id,
     int Order,
@@ -24,7 +35,8 @@ public record WorkflowStepDto(
     string PhaseLabel,
     string Name,
     int? SlaDays,
-    List<WorkflowStepApproverDto> Approvers);
+    List<WorkflowStepApproverDto> Approvers,
+    List<WorkflowStepInnerStepDto> InnerSteps);
 
 public record WorkflowDefinitionDto(
     Guid Id,
@@ -84,9 +96,21 @@ public class GetWorkflowAdminOverviewQueryHandler(
         var definitions = await db.WorkflowDefinitions.AsNoTracking()
             .Include(d => d.Steps.OrderBy(s => s.Order))
                 .ThenInclude(s => s.Approvers)
+            .Include(d => d.Steps)
+                .ThenInclude(s => s.InnerSteps.OrderBy(i => i.Order))
             .OrderByDescending(d => d.Version)
             .ToListAsync(ct);
 
+        // Resolve dept names cho InnerStep.DepartmentName display (Mig 20)
+        var deptIds = definitions
+            .SelectMany(d => d.Steps).SelectMany(s => s.InnerSteps)
+            .Select(i => i.DepartmentId).Distinct().ToList();
+        var deptNames = deptIds.Count == 0
+            ? new Dictionary<Guid, string>()
+            : await db.Departments.AsNoTracking()
+                .Where(d => deptIds.Contains(d.Id))
+                .ToDictionaryAsync(d => d.Id, d => d.Name, ct);
+
         // Resolve user names for User-kind approvers
         var userIds = definitions
             .SelectMany(d => d.Steps)
@@ -130,7 +154,16 @@ public class GetWorkflowAdminOverviewQueryHandler(
                 s.Approvers.Select(a => new WorkflowStepApproverDto(
                     (int)a.Kind,
                     a.AssignmentValue,
-                    ResolveDisplay(a, userNames))).ToList()
+                    ResolveDisplay(a, userNames))).ToList(),
+                s.InnerSteps.OrderBy(i => i.Order).Select(i => new WorkflowStepInnerStepDto(
+                    i.Id,
+                    i.Order,
+                    i.DepartmentId,
+                    deptNames.GetValueOrDefault(i.DepartmentId),
+                    (int)i.PositionLevel,
+                    i.Name,
+                    i.SlaDays,
+                    i.IsRequired)).ToList()
             )).ToList());
 
         var types = Enum.GetValues<ContractType>()
@@ -160,12 +193,23 @@ public class GetWorkflowAdminOverviewQueryHandler(
 
 public record CreateWorkflowStepApproverInput(int Kind, string AssignmentValue);
 
+// Mig 20 — Inner step input cho designer N-stage. InnerSteps optional empty
+// list → service fallback 2-stage Review/Confirm logic legacy Mig 16.
+public record CreateWorkflowStepInnerStepInput(
+    int Order,
+    Guid DepartmentId,
+    int PositionLevel,        // 1=NV, 2=PP, 3=TP
+    string? Name,
+    int? SlaDays,
+    bool IsRequired);
+
 public record CreateWorkflowStepInput(
     int Order,
     int Phase,
     string Name,
     int? SlaDays,
-    List<CreateWorkflowStepApproverInput> Approvers);
+    List<CreateWorkflowStepApproverInput> Approvers,
+    List<CreateWorkflowStepInnerStepInput>? InnerSteps = null);
 
 public record CreateWorkflowDefinitionCommand(
     ContractType ContractType,
@@ -198,6 +242,16 @@ public class CreateWorkflowDefinitionCommandValidator : AbstractValidator<Create
                 app.RuleFor(a => a.Kind).InclusiveBetween(1, 2);
                 app.RuleFor(a => a.AssignmentValue).NotEmpty().MaximumLength(100);
             });
+            step.RuleForEach(s => s.InnerSteps!).ChildRules(inner =>
+            {
+                inner.RuleFor(i => i.Order).GreaterThanOrEqualTo(1);
+                inner.RuleFor(i => i.DepartmentId).NotEmpty();
+                inner.RuleFor(i => i.PositionLevel).InclusiveBetween(1, 3)
+                    .WithMessage("PositionLevel: 1=NV, 2=PP, 3=TP.");
+                inner.RuleFor(i => i.Name).MaximumLength(200);
+                inner.RuleFor(i => i.SlaDays).GreaterThanOrEqualTo(0)
+                    .When(i => i.SlaDays != null);
+            }).When(s => s.InnerSteps != null);
         });
     }
 }
@@ -242,6 +296,15 @@ public class CreateWorkflowDefinitionCommandHandler(IApplicationDbContext db)
                         Kind = (WorkflowApproverKind)a.Kind,
                         AssignmentValue = a.AssignmentValue,
                     }).ToList(),
+                    InnerSteps = (s.InnerSteps ?? new()).OrderBy(i => i.Order).Select(i => new WorkflowStepInnerStep
+                    {
+                        Order = i.Order,
+                        DepartmentId = i.DepartmentId,
+                        PositionLevel = (PositionLevel)i.PositionLevel,
+                        Name = i.Name,
+                        SlaDays = i.SlaDays,
+                        IsRequired = i.IsRequired,
+                    }).ToList(),
                 })
                 .ToList(),
         };