feat(approvals): Approval Flow v2 프런트엔드 전면 개편

- 환경/라우터 모듈에 approval_flow_v2 토글을 추가하고 FeatureFlags 초기화를 연결 (.env*, lib/core/**)
- ApiClient 빌더·ApiRoutes 확장과 ApprovalRepositoryRemote 리팩터링으로 include·액션 시그니처를 정합화
- ApprovalFlow·ApprovalDraft 엔티티/레포/유즈케이스를 도입해 서버 초안과 단계 액션(승인·회수·재상신)을 지원
- Approval 컨트롤러·히스토리·템플릿 페이지와 공유 위젯을 재작성해 감사 로그·회수 UX·템플릿 CRUD를 반영
- Inbound/Outbound/Rental 컨트롤러·페이지에 결재 섹션을 삽입하고 대시보드 pending 카드 요약을 갱신
- SuperportDialog·FormField 등 공통 위젯을 보강하고 승인 위젯 가이드를 추가해 UI 가이드를 정리
- 결재/재고 테스트 픽스처와 단위·위젯·통합 테스트를 확장하고 flutter_test_config로 스테이징 호스트를 허용
- Approval Flow 레포트/플랜 문서를 업데이트하고 ApprovalFlow_System_Integration_and_ChangePlan.md를 추가
- 실행: flutter analyze, flutter test

lib/features/inventory/inbound/presentation/pages/inbound_page.dart

@@ -17,6 +17,13 @@ import 'package:superport_v2/widgets/components/superport_date_picker.dart';
 import 'package:superport_v2/features/inventory/shared/widgets/partner_select_field.dart';
 import 'package:superport_v2/features/inventory/shared/widgets/product_autocomplete_field.dart';
 import 'package:superport_v2/features/inventory/shared/widgets/warehouse_select_field.dart';
+import 'package:superport_v2/features/approvals/request/presentation/controllers/approval_request_controller.dart';
+import 'package:superport_v2/features/approvals/request/presentation/utils/approval_form_initializer.dart';
+import 'package:superport_v2/features/approvals/request/presentation/widgets/approval_step_configurator.dart';
+import 'package:superport_v2/features/approvals/request/presentation/widgets/approval_template_picker.dart';
+import 'package:superport_v2/features/approvals/domain/usecases/get_approval_draft_use_case.dart';
+import 'package:superport_v2/features/approvals/domain/usecases/list_approval_drafts_use_case.dart';
+import 'package:superport_v2/features/approvals/domain/usecases/save_approval_draft_use_case.dart';
 import 'package:superport_v2/core/config/environment.dart';
 import 'package:superport_v2/core/network/failure.dart';
 import 'package:superport_v2/core/permissions/permission_manager.dart';
@@ -126,6 +133,15 @@ class _InboundPageState extends State<InboundPage> {
       lookupRepository: getIt<InventoryLookupRepository>(),
       fallbackStatusOptions: InboundTableSpec.fallbackStatusOptions,
       transactionTypeKeywords: InboundTableSpec.transactionTypeKeywords,
+      saveDraftUseCase: getIt.isRegistered<SaveApprovalDraftUseCase>()
+          ? getIt<SaveApprovalDraftUseCase>()
+          : null,
+      getDraftUseCase: getIt.isRegistered<GetApprovalDraftUseCase>()
+          ? getIt<GetApprovalDraftUseCase>()
+          : null,
+      listDraftsUseCase: getIt.isRegistered<ListApprovalDraftsUseCase>()
+          ? getIt<ListApprovalDraftsUseCase>()
+          : null,
     );
   }
 
@@ -137,6 +153,10 @@ class _InboundPageState extends State<InboundPage> {
     Future.microtask(() async {
       await controller.loadStatusOptions();
       await controller.loadApprovalStatuses();
+      final requester = _resolveCurrentWriter();
+      if (requester != null) {
+        await controller.loadApprovalDraftFromServer(requesterId: requester.id);
+      }
       final hasType = await controller.resolveTransactionType();
       if (!mounted) {
         return;
@@ -1483,6 +1503,25 @@ class _InboundPageState extends State<InboundPage> {
       return '${suggestion.name} (${suggestion.employeeNo})';
     }
 
+    final approvalController = ApprovalRequestController();
+    final defaultRequester = () {
+      final writer = writerSelection;
+      if (writer == null) {
+        return null;
+      }
+      return ApprovalRequestParticipant(
+        id: writer.id,
+        name: writer.name,
+        employeeNo: writer.employeeNo,
+      );
+    }();
+    ApprovalFormInitializer.populate(
+      controller: approvalController,
+      existingApproval: initial?.raw?.approval,
+      draft: _controller?.approvalDraft,
+      defaultRequester: defaultRequester,
+    );
+
     final writerController = TextEditingController(
       text: writerLabel(writerSelection),
     );
@@ -1718,6 +1757,23 @@ class _InboundPageState extends State<InboundPage> {
           return;
         }
 
+        StockTransactionApprovalInput approvalInput;
+        try {
+          approvalInput = approvalController.buildTransactionApprovalInput(
+            approvalStatusId: approvalStatusId,
+            note: approvalNoteValue.isEmpty ? null : approvalNoteValue,
+          );
+        } on StateError catch (error) {
+          updateSaving(false);
+          SuperportToast.error(context, error.message);
+          return;
+        } catch (_) {
+          updateSaving(false);
+          SuperportToast.error(context, '결재 구성을 확인하고 다시 시도하세요.');
+          return;
+        }
+        controller.updateApprovalDraft(approvalInput);
+
         final createLines = lineDrafts
             .map(
               (draft) => TransactionLineCreateInput(
@@ -1738,11 +1794,7 @@ class _InboundPageState extends State<InboundPage> {
           note: remarkValue,
           lines: createLines,
           customers: createCustomers,
-          approval: StockTransactionApprovalInput(
-            requestedById: createdById,
-            approvalStatusId: approvalStatusId,
-            note: approvalNoteValue.isEmpty ? null : approvalNoteValue,
-          ),
+          approval: approvalInput,
         );
         assert(() {
           debugPrint(
@@ -1995,6 +2047,15 @@ class _InboundPageState extends State<InboundPage> {
                     ),
                   ],
                 ),
+                const SizedBox(height: 16),
+                if (initial == null) ...[
+                  ApprovalTemplatePicker(controller: approvalController),
+                  const SizedBox(height: 16),
+                ],
+                ApprovalStepConfigurator(
+                  controller: approvalController,
+                  readOnly: initial != null,
+                ),
                 const SizedBox(height: 24),
                 if (headerNotice != null)
                   Padding(
@@ -2112,6 +2173,7 @@ class _InboundPageState extends State<InboundPage> {
     final disposeApprovalNoteController = approvalNoteController;
     final disposeTransactionTypeController = transactionTypeController;
     final disposeProcessedAt = processedAt;
+    final disposeApprovalController = approvalController;
 
     WidgetsBinding.instance.addPostFrameCallback((_) {
       for (final draft in disposeDrafts) {
@@ -2123,6 +2185,7 @@ class _InboundPageState extends State<InboundPage> {
       disposeApprovalNoteController.dispose();
       disposeTransactionTypeController.dispose();
       disposeProcessedAt.dispose();
+      disposeApprovalController.dispose();
     });
 
     return result;