[CLAUDE] Workflow: App CQRS + API ApprovalWorkflowsV2 (Chunk B)

3 handler MediatR + Validator + Controller cho schema mới Mig 22.

Files:
- Application/ApprovalWorkflowsV2/ApprovalWorkflowV2AdminFeatures.cs
  - GetAwAdminOverviewQuery (filter optional ApplicableType)
  - CreateAwDefinitionCommand + Validator (auto-increment Version
    theo Code, deactivate active version cùng ApplicableType)
  - DeleteAwDefinitionCommand (UAT helper — chưa pin nên unconditional)
  - DTO: AwDefinition/AwStep/AwLevel + TypeSummary
- Application/Common/Interfaces/IApplicationDbContext.cs (3 DbSet)
- Api/Controllers/ApprovalWorkflowsV2Controller.cs
  - Route /api/approval-workflows-v2
  - GET ?applicableType=N | POST | DELETE/{id}
  - Reuse policy Workflows.Read/Workflows.Create

Verify: build OK 0 error, IApplicationDbContext expose 3 DbSet mới.

Next: Chunk C — FE Designer page + route + Layout resolver.

src/Backend/SolutionErp.Application/Common/Interfaces/IApplicationDbContext.cs

@@ -1,4 +1,5 @@
 using Microsoft.EntityFrameworkCore;
+using SolutionErp.Domain.ApprovalWorkflowsV2;
 using SolutionErp.Domain.Budgets;
 using SolutionErp.Domain.Contracts;
 using SolutionErp.Domain.Contracts.Details;
@@ -64,6 +65,12 @@ public interface IApplicationDbContext
     DbSet<PurchaseEvaluationDepartmentOpinion> PurchaseEvaluationDepartmentOpinions { get; }
     DbSet<PurchaseEvaluationDepartmentApproval> PurchaseEvaluationDepartmentApprovals { get; }
 
+    // Quy trình duyệt MỚI (Mig 22 — Session 17): schema riêng UAT trước khi
+    // drop legacy WorkflowDefinition. Cấu trúc: Quy trình > Bước (Phòng) > Cấp (NV cụ thể).
+    DbSet<ApprovalWorkflow> ApprovalWorkflows { get; }
+    DbSet<ApprovalWorkflowStep> ApprovalWorkflowSteps { get; }
+    DbSet<ApprovalWorkflowLevel> ApprovalWorkflowLevels { get; }
+
     // Module Ngân sách (Phase 7)
     DbSet<Budget> Budgets { get; }
     DbSet<BudgetDetail> BudgetDetails { get; }