[CLAUDE] PurchaseEvaluation: Chunk B Service V2 hook UPSERT opinion + DTO + GET include

Service `ApproveV2Async` sau khi log approval (Decision=Approve) → UPSERT
row `PurchaseEvaluationLevelOpinions` cho Cấp hiện tại (auto sync ý kiến
từ comment khi duyệt). Reject KHÔNG sync.

Match level theo ApproverUserId của actor (multi-NV cùng Cấp OR-of-N).
Admin override (actor.Id KHÔNG match) → fallback first level — FE detect
SignedByUserId !== Level.ApproverUserId hiển thị "Admin duyệt thay".

Empty/whitespace comment → "(duyệt — không ý kiến)" placeholder (Q4 bonus).

Helper `ResolveActorFullNameAsync(actorUserId, isSystem, ct)` lookup
denorm SignedByFullName từ Users (fallback "(System)" / "(unknown)").

DTO `PurchaseEvaluationLevelOpinionDto` (15 fields):
- StepOrder/StepName/StepDepartmentId/StepDepartmentName (Bước Phòng)
- LevelOrder/LevelName/ApproverUserId/ApproverFullName (Cấp NV)
- Comment/SignedAt/SignedByUserId/SignedByFullName (sign-off)

GetPurchaseEvaluationQueryHandler:
- Include LevelOpinions
- helper BuildLevelOpinionsAsync JOIN ApprovalWorkflows.Steps.Levels +
  Departments + Users → denorm DTO. Empty list cho phiếu V1 / V2 chưa
  có cấp nào duyệt → FE fallback message.

Verify: dotnet build pass + dotnet test 81 pass (no regression).

Chunk C kế tiếp: FE Section 5 dynamic mirror 2 app.

src/Backend/SolutionErp.Application/PurchaseEvaluations/Dtos/PurchaseEvaluationDtos.cs

@@ -142,6 +142,27 @@ public record PurchaseEvaluationDepartmentOpinionDto(
     Guid? UserId,
     string? UserName);
 
+// Mig 26 (Session 19) — Ý kiến cấp duyệt V2 dynamic theo ApprovalWorkflowLevel.
+// FE Section 5 render dynamic: forEach Step → forEach Level → 1 OpinionBox.
+// Service ApproveV2Async UPSERT tự động khi NV duyệt (Q1=1B). Comment empty
+// fallback "(duyệt — không ý kiến)". `SignedByUserId !== ApproverUserId` →
+// FE show banner "Admin duyệt thay <ApproverFullName>".
+public record PurchaseEvaluationLevelOpinionDto(
+    Guid Id,
+    Guid ApprovalWorkflowLevelId,
+    int StepOrder,
+    string StepName,
+    Guid? StepDepartmentId,
+    string? StepDepartmentName,
+    int LevelOrder,
+    string? LevelName,
+    Guid ApproverUserId,
+    string? ApproverFullName,
+    string Comment,
+    DateTime SignedAt,
+    Guid SignedByUserId,
+    string SignedByFullName);
+
 public record PurchaseEvaluationDetailBundleDto(
     Guid Id,
     string? MaPhieu,
@@ -180,4 +201,7 @@ public record PurchaseEvaluationDetailBundleDto(
     List<PurchaseEvaluationApprovalDto> Approvals,
     List<PurchaseEvaluationAttachmentDto> Attachments,
     List<PurchaseEvaluationDepartmentOpinionDto> DepartmentOpinions,
+    // Mig 26 (Session 19) — Section 5 V2 dynamic. Empty list cho phiếu V1
+    // legacy hoặc phiếu V2 chưa có cấp nào duyệt → FE fallback message.
+    List<PurchaseEvaluationLevelOpinionDto> LevelOpinions,
     PurchaseEvaluationWorkflowSummaryDto Workflow);

src/Backend/SolutionErp.Application/PurchaseEvaluations/PurchaseEvaluationFeatures.cs

@@ -447,6 +447,7 @@ public class GetPurchaseEvaluationQueryHandler(
             .Include(x => x.Approvals)
             .Include(x => x.Attachments)
             .Include(x => x.DepartmentOpinions)
+            .Include(x => x.LevelOpinions)  // Mig 26 — Section 5 V2 dynamic
             .FirstOrDefaultAsync(x => x.Id == request.Id, ct)
             ?? throw new NotFoundException("PurchaseEvaluation", request.Id);
 
@@ -687,12 +688,73 @@ public class GetPurchaseEvaluationQueryHandler(
                     o.Id, o.Kind, KindLabel(o.Kind),
                     o.Opinion, o.SignedAt, o.UserId, o.UserName))
                 .ToList(),
+            await BuildLevelOpinionsAsync(e, ct),
             new PurchaseEvaluationWorkflowSummaryDto(
                 policy.Name, policy.Description,
                 policy.ActivePhases.ToList(),
                 policy.NextPhasesFrom(e.Phase).ToList()));
     }
 
+    // Mig 26 (Session 19) — Build LevelOpinionDto[] cho Section 5 dynamic.
+    // Phiếu V1 (no ApprovalWorkflowId) hoặc chưa có cấp duyệt nào → empty list,
+    // FE hiển thị fallback message. JOIN Steps/Levels lấy meta (StepOrder, name,
+    // DepartmentName, ApproverFullName) — denorm vào DTO để FE render trực tiếp.
+    private async Task<List<PurchaseEvaluationLevelOpinionDto>> BuildLevelOpinionsAsync(
+        PurchaseEvaluation e, CancellationToken ct)
+    {
+        var result = new List<PurchaseEvaluationLevelOpinionDto>();
+        if (e.LevelOpinions.Count == 0 || e.ApprovalWorkflowId is not Guid wfV2Id)
+            return result;
+
+        var aw = await db.ApprovalWorkflows.AsNoTracking()
+            .Include(w => w.Steps).ThenInclude(s => s.Levels)
+            .FirstOrDefaultAsync(w => w.Id == wfV2Id, ct);
+        if (aw is null) return result;
+
+        var levelMap = aw.Steps
+            .SelectMany(s => s.Levels.Select(l => new { Step = s, Level = l }))
+            .ToDictionary(x => x.Level.Id);
+
+        var deptIds = aw.Steps.Where(s => s.DepartmentId.HasValue)
+            .Select(s => s.DepartmentId!.Value).Distinct().ToList();
+        var depts = await db.Departments.AsNoTracking()
+            .Where(d => deptIds.Contains(d.Id))
+            .ToDictionaryAsync(d => d.Id, d => d.Name, ct);
+
+        var userIds = new HashSet<Guid>(
+            aw.Steps.SelectMany(s => s.Levels.Select(l => l.ApproverUserId)));
+        // SignedByUserId có thể KHÁC ApproverUserId (Admin override) — load thêm.
+        foreach (var op in e.LevelOpinions) userIds.Add(op.SignedByUserId);
+        var users = await userManager.Users.AsNoTracking()
+            .Where(u => userIds.Contains(u.Id))
+            .ToDictionaryAsync(u => u.Id, u => u.FullName, ct);
+
+        foreach (var op in e.LevelOpinions.OrderBy(o => o.SignedAt))
+        {
+            if (!levelMap.TryGetValue(op.ApprovalWorkflowLevelId, out var meta)) continue;
+            string? deptName = meta.Step.DepartmentId.HasValue
+                && depts.TryGetValue(meta.Step.DepartmentId.Value, out var dn)
+                ? dn : null;
+            string? approverFullName = users.TryGetValue(meta.Level.ApproverUserId, out var an) ? an : null;
+            result.Add(new PurchaseEvaluationLevelOpinionDto(
+                op.Id,
+                op.ApprovalWorkflowLevelId,
+                meta.Step.Order,
+                meta.Step.Name,
+                meta.Step.DepartmentId,
+                deptName,
+                meta.Level.Order,
+                meta.Level.Name,
+                meta.Level.ApproverUserId,
+                approverFullName,
+                op.Comment ?? "",
+                op.SignedAt,
+                op.SignedByUserId,
+                op.SignedByFullName));
+        }
+        return result;
+    }
+
     private static string KindLabel(PeDepartmentKind k) => k switch
     {
         PeDepartmentKind.PheDuyet => "Phê duyệt",