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

test/features/approvals/domain/usecases/approval_decision_use_cases_test.dart

@@ -0,0 +1,160 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+
+import 'package:superport_v2/features/approvals/domain/entities/approval.dart';
+import 'package:superport_v2/features/approvals/domain/entities/approval_proceed_status.dart';
+import 'package:superport_v2/features/approvals/domain/repositories/approval_repository.dart';
+import 'package:superport_v2/features/approvals/domain/usecases/approve_approval_use_case.dart';
+import 'package:superport_v2/features/approvals/domain/usecases/reject_approval_use_case.dart';
+
+class _MockApprovalRepository extends Mock implements ApprovalRepository {}
+
+void main() {
+  late ApprovalRepository repository;
+  late ApproveApprovalUseCase approveUseCase;
+  late RejectApprovalUseCase rejectUseCase;
+
+  setUpAll(() {
+    registerFallbackValue(ApprovalDecisionInput(approvalId: 0, actorId: 0));
+  });
+
+  setUp(() {
+    repository = _MockApprovalRepository();
+    approveUseCase = ApproveApprovalUseCase(repository: repository);
+    rejectUseCase = RejectApprovalUseCase(repository: repository);
+  });
+
+  group('ApproveApprovalUseCase', () {
+    test('권한이 있으면 승인 요청을 위임한다', () async {
+      const approvalId = 10;
+      const actorId = 7;
+      final input = ApprovalDecisionInput(
+        approvalId: approvalId,
+        actorId: actorId,
+      );
+      final approval = _buildApproval(id: approvalId);
+
+      when(() => repository.canProceed(approvalId)).thenAnswer(
+        (_) async =>
+            ApprovalProceedStatus(approvalId: approvalId, canProceed: true),
+      );
+      when(() => repository.approve(any())).thenAnswer((_) async => approval);
+
+      final flow = await approveUseCase(input);
+
+      expect(flow.id, approvalId);
+      verify(() => repository.canProceed(approvalId)).called(1);
+      final captured =
+          verify(() => repository.approve(captureAny())).captured.single
+              as ApprovalDecisionInput;
+      expect(captured.approvalId, approvalId);
+      expect(captured.actorId, actorId);
+    });
+
+    test('권한이 없으면 StateError를 던지고 승인 요청을 하지 않는다', () async {
+      const approvalId = 99;
+      final input = ApprovalDecisionInput(approvalId: approvalId, actorId: 3);
+      when(() => repository.canProceed(approvalId)).thenAnswer(
+        (_) async => ApprovalProceedStatus(
+          approvalId: approvalId,
+          canProceed: false,
+          reason: '승인 권한이 없습니다.',
+        ),
+      );
+
+      expect(
+        () => approveUseCase(input),
+        throwsA(
+          isA<StateError>().having(
+            (error) => error.message,
+            'message',
+            contains('승인 권한이 없습니다.'),
+          ),
+        ),
+      );
+      verify(() => repository.canProceed(approvalId)).called(1);
+      verifyNever(() => repository.approve(any()));
+    });
+  });
+
+  group('RejectApprovalUseCase', () {
+    test('권한이 있으면 반려 요청을 위임한다', () async {
+      const approvalId = 70;
+      const actorId = 11;
+      final input = ApprovalDecisionInput(
+        approvalId: approvalId,
+        actorId: actorId,
+      );
+      final approval = _buildApproval(id: approvalId);
+
+      when(() => repository.canProceed(approvalId)).thenAnswer(
+        (_) async =>
+            ApprovalProceedStatus(approvalId: approvalId, canProceed: true),
+      );
+      when(() => repository.reject(any())).thenAnswer((_) async => approval);
+
+      final flow = await rejectUseCase(input);
+
+      expect(flow.id, approvalId);
+      verify(() => repository.canProceed(approvalId)).called(1);
+      final captured =
+          verify(() => repository.reject(captureAny())).captured.single
+              as ApprovalDecisionInput;
+      expect(captured.approvalId, approvalId);
+      expect(captured.actorId, actorId);
+    });
+
+    test('권한이 없으면 StateError를 던지고 반려 요청을 하지 않는다', () async {
+      const approvalId = 45;
+      final input = ApprovalDecisionInput(approvalId: approvalId, actorId: 9);
+
+      when(() => repository.canProceed(approvalId)).thenAnswer(
+        (_) async =>
+            ApprovalProceedStatus(approvalId: approvalId, canProceed: false),
+      );
+
+      expect(
+        () => rejectUseCase(input),
+        throwsA(
+          isA<StateError>().having(
+            (error) => error.message,
+            'message',
+            contains('결재를 진행할 권한이 없습니다.'),
+          ),
+        ),
+      );
+      verify(() => repository.canProceed(approvalId)).called(1);
+      verifyNever(() => repository.reject(any()));
+    });
+  });
+}
+
+Approval _buildApproval({required int id}) {
+  final status = ApprovalStatus(id: 1, name: '진행중');
+  final approver = ApprovalApprover(id: 5, employeeNo: 'EMP-5', name: '김승인');
+  return Approval(
+    id: id,
+    approvalNo: 'APP-$id',
+    transactionNo: 'TRX-$id',
+    status: status,
+    currentStep: ApprovalStep(
+      id: 10,
+      stepOrder: 1,
+      approver: approver,
+      status: status,
+      assignedAt: DateTime.utc(2025, 1, 1, 9),
+    ),
+    requester: ApprovalRequester(id: 2, employeeNo: 'EMP-2', name: '상신자'),
+    requestedAt: DateTime.utc(2025, 1, 1, 9),
+    steps: [
+      ApprovalStep(
+        id: 10,
+        stepOrder: 1,
+        approver: approver,
+        status: status,
+        assignedAt: DateTime.utc(2025, 1, 1, 9),
+      ),
+    ],
+    histories: const [],
+  );
+}