[CLAUDE] Phase5.1: Security headers + account lockout + Users management

Security hardening:
- Api/Middleware/SecurityHeadersMiddleware MOI: remove server fingerprint (Server, X-Powered-By, ...), add X-Content-Type-Options:nosniff, X-Frame-Options:DENY, Referrer-Policy:strict-origin-when-cross-origin, Permissions-Policy (disable geolocation/mic/cam/payment), X-Permitted-Cross-Domain-Policies:none, CSP (default-src 'self' + img data: + style inline for Tailwind + frame-ancestors 'none'). Skip CSP tren /swagger (dung inline script).
- Program.cs wire UseMiddleware SecurityHeadersMiddleware first in pipeline
- Infrastructure/DependencyInjection Identity options:
  - Password.RequiredLength config-driven (Identity:Password:RequiredLength, default 8 dev, override 12+ prod)
  - Lockout: DefaultLockoutTimeSpan (15min), MaxFailedAccessAttempts (5), AllowedForNewUsers=true — all config-driven
- LoginCommandHandler: IsLockedOutAsync check truoc → throw voi deadline message, AccessFailedAsync khi sai password, ResetAccessFailedCountAsync khi login thanh cong

Users management:
- Application/Users/UserFeatures.cs: 8 CQRS (ListUsersQuery paging+search, GetUserQuery, CreateUserCommand + Validator, UpdateUserCommand voi self-disable protection, AssignRolesCommand voi self-demote protection (khong tu go Admin), ResetPasswordCommand (invalidate refresh token + unlock), UnlockUserCommand)
- UserDto: Id, Email, FullName, IsActive, IsLocked (computed tu LockoutEnd), CreatedAt, Roles
- Api/Controllers/UsersController: 7 endpoint (Users.Read/Create/Update policies):
  - GET / (list paged), GET /{id}, POST /, PUT /{id}, PUT /{id}/roles, POST /{id}/reset-password, POST /{id}/unlock
- using alias ValidationException = Application.Common.Exceptions.ValidationException (fix ambiguity voi FluentValidation)

Frontend fe-admin:
- types/users.ts MOI: User type + AVAILABLE_ROLES 12 role (match BE AppRoles.cs) + RoleLabel Vietnamese
- pages/system/UsersPage.tsx MOI:
  - DataTable columns: Email (mono), FullName, Roles (badge chips voi Vietnamese label), IsActive (CheckCircle/XCircle), IsLocked (KeyRound red), CreatedAt
  - Actions per row (PermissionGuard Users.Update wrap): Gan role (Shield icon → Dialog grid 12 checkbox), Reset password (KeyRound → Dialog voi warning user se bi logout), Unlock (Unlock icon, chi hien khi isLocked), Toggle active (XCircle/CheckCircle)
  - Create user dialog: email + fullName + password (min 8) + grid 12 role checkbox
- Route /system/users vao App.tsx

E2E verified:
- Security headers present tren moi response (check qua curl -I)
- POST /api/users voi roles: [Drafter] → 201 + id
- GET /api/users → paged voi 2 user (admin + new test.drafter)
- TS check fe-admin → pass
- dotnet build → 0 errors

Docs:
- docs/STATUS.md: Phase 5.1 xong, cumulative BE 3700 LOC, 42 endpoints, 17 FE pages
- docs/HANDOFF.md: phase table update row Phase 5.1, last updated timestamp
- docs/changelog/migration-todos.md: tick 6 items Phase 5.1 + 4 items remaining (IDOR, deps scan, admin warning, Roles CRUD)
- docs/changelog/sessions/2026-04-21-1630-phase5-1-security-users.md: session log

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

docs/HANDOFF.md

@@ -1,6 +1,6 @@
 # HANDOFF — Brief 5 phút cho session tiếp theo
 
-**Last updated:** 2026-04-21 15:30 (cuối Phase 5 Prep)
+**Last updated:** 2026-04-21 16:30 (cuối Phase 5.1 Security + Users Mgmt)
 
 ## Ở đâu rồi?
 
@@ -15,9 +15,9 @@
 | 3 Workflow iteration 2 (SLA + notify + attachment) | 📝 Optional |
 | 4 Report MVP (Dashboard + Excel) | ✅ Done |
 | 4 Report iteration 2 | 📝 Optional |
-| **5 Prep (infra + scripts + guides + refresh token)** | ✅ Done |
+| 5 Prep (infra + scripts + guides + refresh token) | ✅ Done |
+| **5.1 Security + Users Mgmt (headers, lockout, Users CRUD)** | ✅ Done (IDOR + deps scan còn) |
 | 5 Deploy production (cần Gitea URL) | 📋 Next |
-| 5.1 Security hardening (headers, lockout, IDOR) | 📋 Queue |
 
 ## Run nhanh