[CLAUDE] Tests: PE N-stage workflow approval (6 test) + IdentityFixture extend (Chunk D)

PeNStageApprovalTests.cs (NEW, 6 test) cover N-stage logic Mig 18:

1. NStage_FirstInner_NV_Approve_Blocks_Phase_Transition
   NV.PRO duyệt cấp 1 → 1 row InnerStepId set, phase chưa đổi (còn 2 cấp).

2. NStage_All_3_Levels_Sequential_Pass_Allow_Phase_Transition
   NV → PP → TP duyệt lần lượt → 3 rows + phase chuyển. Order asc enforce.

3. NStage_TP_Bypass_Skips_Lower_Levels_Same_Dept
   TP có CanBypassReview → 1 transition tạo 3 rows (NV+PP IsBypassed=true,
   TP exact match). Audit chuẩn.

4. NStage_Wrong_Department_Throws_Forbidden
   Actor dept khác inner step's dept → ForbiddenException.

5. NStage_Reject_Clears_InnerStep_Rows_At_Phase
   NV approve → 1 row. Reject → DangSoanThao + RejectedFromPhase set +
   N-stage rows cleared (resume sẽ approve lại).

6. LegacyFallback_NoInnerSteps_Uses_2Stage_Logic
   PE không pin WorkflowDefinitionId → service fallback hardcoded policy →
   no inner steps → legacy 2-stage Stage=Review/Confirm logic kick in.

IdentityFixture.CreateUserAsync extend +PositionLevel? param (default null
cho admin/system user).

Helper SeedWorkflowDefinitionAsync: tạo definition với 2 steps adjacent
(ChoPurchasing có inner steps + ChoCCM next) — đủ cho FromDefinition build
transition policy guard pass actor role Procurement.

Verify: 83 → **89 test pass** (54 Domain + 35 Infra: 17 codegen + 6 PE WF
versioning + 6 PE 2-stage + 6 PE N-stage). 0 fail.

Pending Chunk E: API endpoints (PATCH /users/{id}/position-level + DTO
extend in PeWorkflowsController bind tự động).

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

tests/SolutionErp.Infrastructure.Tests/Common/IdentityFixture.cs

@@ -68,13 +68,14 @@ public sealed class IdentityFixture : IDisposable
         ctx.Database.EnsureCreated();
     }
 
-    // Helper: tạo user + assign roles + gán DepartmentId. Reuse trong nhiều test.
+    // Helper: tạo user + assign roles + gán DepartmentId + PositionLevel. Reuse trong nhiều test.
     public async Task<User> CreateUserAsync(
         string email,
         string fullName,
         Guid? departmentId,
         string[] roles,
-        bool canBypassReview = false)
+        bool canBypassReview = false,
+        PositionLevel? positionLevel = null)
     {
         var um = Services.GetRequiredService<UserManager<User>>();
         var rm = Services.GetRequiredService<RoleManager<Role>>();
@@ -95,6 +96,7 @@ public sealed class IdentityFixture : IDisposable
             FullName = fullName,
             DepartmentId = departmentId,
             CanBypassReview = canBypassReview,
+            PositionLevel = positionLevel,
             IsActive = true,
         };
         var created = await um.CreateAsync(user, "Test@123");