[CLAUDE] Infra+App+Api+FE: Chunk E4 — HĐ 2-stage dept approval (mirror PE)

Mở rộng 2-stage logic từ PE sang Contract workflow (Migration 16 đã có schema):

BE Service:
- ContractWorkflowService thêm UserManager<User> DI
- Mirror logic 2-stage từ PurchaseEvaluationWorkflowService.TransitionAsync
  Sau policy guard, trước gen mã HĐ:
  - User.DepartmentId != null + actor không admin/system + KHÔNG resume
    - DeptManager (TPB) → Stage=Confirm trực tiếp
    - CanBypassReview=true → Stage=Confirm + IsBypassed=true
    - Else (NV) → Stage=Review only, BLOCK transition
  - Insert ContractDepartmentApproval row (UPSERT theo UNIQUE)
  - Block transition khi chưa có Stage=Confirm:
    - Insert ContractApproval (FromPhase=ToPhase=fromPhase, [Review NV] comment)
    - Insert ContractChangelog "đã review, chờ TPB confirm"
    - Notify TPB cùng dept (UserManager filter DeptManager role)
    - Return early — phase KHÔNG đổi

App + Api:
- ContractDepartmentApprovalFeatures.cs (List query mirror PE)
- ContractsController endpoint GET /contracts/{id}/department-approvals

FE (cả fe-admin + fe-user):
- types/contracts.ts thêm ApprovalStage const + ContractDepartmentApproval type
- WorkflowHistoryPanel section "Tiến trình duyệt 2-cấp phòng ban":
  - Group by phase × dept, show Review NV + Confirm TPB
  - Highlight amber "chờ TPB confirm" khi current phase có Review chưa Confirm
  - Badge fuchsia "bypass" khi NV.CanBypassReview=true
  - Insert giữa WorkflowSummaryCard và Lịch sử duyệt
- Mirror cả 2 app (rule §3.9)

Use case mirror PE: HĐ ở phase DangGopY (P.CCM) — nv.cao (NV) duyệt thì
phase KHÔNG đổi (Review only), chờ ccm.tran (TPB) confirm mới sang DangXetDuyet.

Build: BE pass + FE pass cả 2 + 77 test pass.

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

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

@@ -0,0 +1,80 @@
+using MediatR;
+using Microsoft.EntityFrameworkCore;
+using SolutionErp.Application.Common.Interfaces;
+using SolutionErp.Domain.Common;
+using SolutionErp.Domain.Contracts;
+
+namespace SolutionErp.Application.Contracts;
+
+// 2-stage department approval list cho HĐ (Phase 9 — Migration 16).
+// Mirror PE — query để FE hiển thị progress per phase × dept.
+//
+// FE Workflow Panel HĐ render dạng timeline:
+// - Phase DangGopY (CCM):
+//   - Stage Review: nv.cao (NV) — 14:30
+//   - Stage Confirm: ccm.tran (TPB) — 14:35 → unlock transition
+//
+// Insertion + Block logic ở ContractWorkflowService.TransitionAsync.
+
+public record ListContractDepartmentApprovalsQuery(Guid ContractId)
+    : IRequest<List<ContractDepartmentApprovalDto>>;
+
+public record ContractDepartmentApprovalDto(
+    Guid Id,
+    int PhaseAtApproval,
+    Guid DepartmentId,
+    string? DepartmentName,
+    ApprovalStage Stage,
+    Guid ApproverUserId,
+    string? ApproverName,
+    string? ApproverRoleSnapshot,
+    string? Comment,
+    DateTime ApprovedAt,
+    bool IsBypassed);
+
+public class ListContractDepartmentApprovalsQueryHandler(IApplicationDbContext db)
+    : IRequestHandler<ListContractDepartmentApprovalsQuery, List<ContractDepartmentApprovalDto>>
+{
+    public async Task<List<ContractDepartmentApprovalDto>> Handle(
+        ListContractDepartmentApprovalsQuery request, CancellationToken ct)
+    {
+        var rows = await (
+            from a in db.ContractDepartmentApprovals.AsNoTracking()
+            join d in db.Departments.AsNoTracking() on a.DepartmentId equals d.Id into deptJoin
+            from d in deptJoin.DefaultIfEmpty()
+            where a.ContractId == request.ContractId
+            orderby a.PhaseAtApproval, a.Stage, a.ApprovedAt
+            select new
+            {
+                a.Id,
+                a.PhaseAtApproval,
+                a.DepartmentId,
+                DepartmentName = d != null ? d.Name : null,
+                a.Stage,
+                a.ApproverUserId,
+                a.ApproverRoleSnapshot,
+                a.Comment,
+                a.ApprovedAt,
+                a.IsBypassed,
+            }).ToListAsync(ct);
+
+        var userIds = rows.Select(r => r.ApproverUserId).Distinct().ToList();
+        var users = await db.Users.AsNoTracking()
+            .Where(u => userIds.Contains(u.Id))
+            .Select(u => new { u.Id, Name = u.FullName ?? u.Email ?? "" })
+            .ToDictionaryAsync(u => u.Id, u => u.Name, ct);
+
+        return rows.Select(r => new ContractDepartmentApprovalDto(
+            r.Id,
+            r.PhaseAtApproval,
+            r.DepartmentId,
+            r.DepartmentName,
+            r.Stage,
+            r.ApproverUserId,
+            users.TryGetValue(r.ApproverUserId, out var n) ? n : null,
+            r.ApproverRoleSnapshot,
+            r.Comment,
+            r.ApprovedAt,
+            r.IsBypassed)).ToList();
+    }
+}