[CLAUDE] Domain+Infra+App+Api+FE-Admin: versioned workflow per ContractType

User yêu cầu: mỗi loại HĐ có quy trình riêng với admin add roles + users
vào từng bước. Khi tạo version mới → HĐ tương lai chạy theo, HĐ cũ giữ
version cũ.

Domain:
- WorkflowDefinition (Code + Version + ContractType + IsActive + Steps)
- WorkflowStep (Order + Phase + Name + SlaDays + Approvers)
- WorkflowStepApprover (Kind: Role/User + AssignmentValue)
- Contract.WorkflowDefinitionId — pinned at creation
- WorkflowPolicyRegistry.FromDefinition() — build runtime policy từ DB

Infrastructure:
- EF config + migration AddVersionedWorkflows (3 table mới)
- DbInitializer.SeedWorkflowDefinitionsAsync: v01 per 7 ContractType,
  steps sinh từ hardcoded WorkflowPolicies (Role approvers).
- ContractWorkflowService.TransitionAsync: load pinned WorkflowDefinition
  → FromDefinition(), fallback cho HĐ cũ không có pin.

Application:
- CreateContractCommand pin WorkflowDefinitionId = active version cho type
- ContractFeatures.Get(id): load pinned def cho workflow summary
- WorkflowAdminFeatures: GetWorkflowAdminOverviewQuery (7 types + active
  + history + ContractsUsingCount), CreateWorkflowDefinitionCommand
  (validate payload, auto-increment version, deactivate old).

Api:
- GET /api/workflows trả overview
- POST /api/workflows tạo version mới (deactivate old)

FE /system/workflows:
- Tabs per 7 ContractType, mỗi tab hiện active version + lịch sử
- DefinitionCard: steps với badge role/user + SLA + archived indicator
  hiện "N HĐ còn chạy" cho version cũ
- WorkflowDesigner modal: form code/name/desc + danh sách steps
  (phase/name/SLA) + approvers (+ Role hoặc + User). Drop step ok.
  Clone từ version hiện tại để tạo v02 có điểm start sensible.
- Amber banner: HĐ cũ không bị ảnh hưởng khi tạo version mới

Invariants được giữ:
- Unique (Code, Version) index
- Chỉ 1 version IsActive per ContractType tại 1 thời điểm
- Set default sẽ auto xóa override → respect legacy override table
- Role-kind approvers drive transition guards; User-kind fallback
  DeptManager role cho v1 (user-level targeting = iteration 2)

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

src/Backend/SolutionErp.Api/Controllers/WorkflowsController.cs

@@ -2,7 +2,6 @@ using MediatR;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using SolutionErp.Application.Contracts;
-using SolutionErp.Domain.Contracts;
 
 namespace SolutionErp.Api.Controllers;
 
@@ -15,13 +14,11 @@ public class WorkflowsController(IMediator mediator) : ControllerBase
     public async Task<ActionResult<WorkflowAdminOverviewDto>> Overview(CancellationToken ct)
         => Ok(await mediator.Send(new GetWorkflowAdminOverviewQuery(), ct));
 
-    [HttpPut("{contractType:int}")]
-    [Authorize(Policy = "Workflows.Update")]
-    public async Task<IActionResult> SetAssignment(int contractType, [FromBody] SetWorkflowAssignmentBody body, CancellationToken ct)
+    [HttpPost]
+    [Authorize(Policy = "Workflows.Create")]
+    public async Task<ActionResult<object>> Create([FromBody] CreateWorkflowDefinitionCommand cmd, CancellationToken ct)
     {
-        await mediator.Send(new SetWorkflowAssignmentCommand((ContractType)contractType, body.PolicyName), ct);
-        return NoContent();
+        var id = await mediator.Send(cmd, ct);
+        return Ok(new { id });
     }
 }
-
-public record SetWorkflowAssignmentBody(string PolicyName);