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/transactions/data/dtos/stock_transaction_dto.dart

@@ -1,5 +1,6 @@
 import 'package:superport_v2/core/common/models/paginated_result.dart';
 import 'package:superport_v2/core/common/utils/json_utils.dart';
+import 'package:superport_v2/features/approvals/data/dtos/approval_dto.dart';
 
 import '../../domain/entities/stock_transaction.dart';
 
@@ -38,7 +39,7 @@ class StockTransactionDto {
   final DateTime? updatedAt;
   final List<StockTransactionLine> lines;
   final List<StockTransactionCustomer> customers;
-  final StockTransactionApprovalSummary? approval;
+  final ApprovalDto? approval;
   final DateTime? expectedReturnDate;
 
   /// JSON 객체를 DTO로 변환한다.
@@ -86,7 +87,7 @@ class StockTransactionDto {
       updatedAt: updatedAt,
       lines: lines,
       customers: customers,
-      approval: approval,
+      approval: approval?.toEntity(),
       expectedReturnDate: expectedReturnDate,
     );
   }
@@ -328,43 +329,21 @@ StockTransactionCustomerSummary _parseCustomer(
   );
 }
 
-StockTransactionApprovalSummary? _parseApproval(dynamic raw) {
+ApprovalDto? _parseApproval(dynamic raw) {
   final map = _mapOrEmpty(raw);
   if (map.isEmpty) {
     return null;
   }
-  final statusMap = _firstNonEmptyMap([map['approval_status'], map['status']]);
-  return StockTransactionApprovalSummary(
-    id: map['id'] as int? ?? 0,
-    approvalNo:
-        map['approval_no'] as String? ?? map['approvalNo'] as String? ?? '',
-    status: statusMap.isEmpty
-        ? null
-        : StockTransactionApprovalStatusSummary(
-            id: statusMap['id'] as int? ?? statusMap['status_id'] as int? ?? 0,
-            name:
-                statusMap['name'] as String? ??
-                statusMap['status_name'] as String? ??
-                '-',
-            isBlocking:
-                statusMap['is_blocking_next'] as bool? ??
-                statusMap['isBlocking'] as bool?,
-          ),
-  );
+  try {
+    return ApprovalDto.fromJson(map);
+  } catch (_) {
+    return null;
+  }
 }
 
 Map<String, dynamic> _mapOrEmpty(dynamic value) =>
     value is Map<String, dynamic> ? value : const <String, dynamic>{};
 
-Map<String, dynamic> _firstNonEmptyMap(List<dynamic> candidates) {
-  for (final candidate in candidates) {
-    if (candidate is Map<String, dynamic> && candidate.isNotEmpty) {
-      return candidate;
-    }
-  }
-  return const <String, dynamic>{};
-}
-
 int _readQuantity(Object? value) {
   if (value is int) {
     return value;

lib/features/inventory/transactions/data/repositories/transaction_line_repository_remote.dart

@@ -49,9 +49,6 @@ class TransactionLineRepositoryRemote implements TransactionLineRepository {
 
   @override
   Future<void> restoreLine(int lineId) async {
-    await _api.post<void>(
-      '$_linePath/$lineId/restore',
-    );
+    await _api.post<void>('$_linePath/$lineId/restore');
   }
-
 }

lib/features/inventory/transactions/domain/entities/stock_transaction.dart

@@ -1,3 +1,5 @@
+import 'package:superport_v2/features/approvals/domain/entities/approval.dart';
+
 /// 재고 트랜잭션 도메인 엔티티
 ///
 /// - 입고/출고/대여 공통으로 사용되는 헤더와 라인, 고객 연결 정보를 포함한다.
@@ -33,7 +35,7 @@ class StockTransaction {
   final DateTime? updatedAt;
   final List<StockTransactionLine> lines;
   final List<StockTransactionCustomer> customers;
-  final StockTransactionApprovalSummary? approval;
+  final Approval? approval;
   final DateTime? expectedReturnDate;
 
   int get itemCount => lines.length;
@@ -57,7 +59,7 @@ class StockTransaction {
     DateTime? updatedAt,
     List<StockTransactionLine>? lines,
     List<StockTransactionCustomer>? customers,
-    StockTransactionApprovalSummary? approval,
+    Approval? approval,
     DateTime? expectedReturnDate,
   }) {
     return StockTransaction(
@@ -200,32 +202,6 @@ class StockTransactionUomSummary {
   final String name;
 }
 
-/// 결재 요약 정보
-class StockTransactionApprovalSummary {
-  StockTransactionApprovalSummary({
-    required this.id,
-    required this.approvalNo,
-    this.status,
-  });
-
-  final int id;
-  final String approvalNo;
-  final StockTransactionApprovalStatusSummary? status;
-}
-
-/// 결재 상태 요약 정보
-class StockTransactionApprovalStatusSummary {
-  StockTransactionApprovalStatusSummary({
-    required this.id,
-    required this.name,
-    this.isBlocking,
-  });
-
-  final int id;
-  final String name;
-  final bool? isBlocking;
-}
-
 extension StockTransactionLineX on List<StockTransactionLine> {
   /// 라인 품목 가격 총액을 계산한다.
   double get totalAmount =>

lib/features/inventory/transactions/domain/entities/stock_transaction_input.dart

@@ -1,3 +1,5 @@
+import 'package:superport_v2/features/approvals/domain/entities/approval.dart';
+
 /// 재고 트랜잭션 생성 입력 모델.
 class StockTransactionCreateInput {
   StockTransactionCreateInput({
@@ -10,7 +12,7 @@ class StockTransactionCreateInput {
     this.expectedReturnDate,
     this.lines = const [],
     this.customers = const [],
-    this.approval,
+    required this.approval,
   });
 
   final int transactionTypeId;
@@ -22,7 +24,7 @@ class StockTransactionCreateInput {
   final DateTime? expectedReturnDate;
   final List<TransactionLineCreateInput> lines;
   final List<TransactionCustomerCreateInput> customers;
-  final StockTransactionApprovalInput? approval;
+  final StockTransactionApprovalInput approval;
 
   Map<String, dynamic> toPayload() {
     final sanitizedNote = note?.trim();
@@ -43,7 +45,7 @@ class StockTransactionCreateInput {
         'expected_return_date': _formatNaiveDate(expectedReturnDate!),
       'lines': linePayloads,
       'customers': customerPayloads,
-      if (approval != null) 'approval': approval!.toJson(),
+      'approval': approval.toJson(),
     };
   }
 }
@@ -213,20 +215,59 @@ class StockTransactionApprovalInput {
   StockTransactionApprovalInput({
     required this.requestedById,
     this.approvalStatusId,
+    this.templateId,
+    this.finalApproverId,
+    this.requestedAt,
+    this.decidedAt,
+    this.cancelledAt,
+    this.lastActionAt,
+    this.title,
+    this.summary,
     this.note,
+    this.metadata,
+    this.steps = const [],
   });
 
   final int requestedById;
   final int? approvalStatusId;
+  final int? templateId;
+  final int? finalApproverId;
+  final DateTime? requestedAt;
+  final DateTime? decidedAt;
+  final DateTime? cancelledAt;
+  final DateTime? lastActionAt;
+  final String? title;
+  final String? summary;
   final String? note;
+  final Map<String, dynamic>? metadata;
+  final List<ApprovalStepAssignmentItem> steps;
 
   Map<String, dynamic> toJson() {
     final trimmedNote = note?.trim();
-    return {
-      if (approvalStatusId != null) 'approval_status_id': approvalStatusId,
+    final trimmedTitle = title?.trim();
+    final trimmedSummary = summary?.trim();
+    final payload = <String, dynamic>{
       'requested_by_id': requestedById,
+      if (approvalStatusId != null) 'approval_status_id': approvalStatusId,
+      if (templateId != null) 'template_id': templateId,
+      if (finalApproverId != null) 'final_approver_id': finalApproverId,
+      if (requestedAt != null) 'requested_at': _formatIsoUtc(requestedAt!),
+      if (decidedAt != null) 'decided_at': _formatIsoUtc(decidedAt!),
+      if (cancelledAt != null) 'cancelled_at': _formatIsoUtc(cancelledAt!),
+      if (lastActionAt != null) 'last_action_at': _formatIsoUtc(lastActionAt!),
+      if (trimmedTitle != null && trimmedTitle.isNotEmpty)
+        'title': trimmedTitle,
+      if (trimmedSummary != null && trimmedSummary.isNotEmpty)
+        'summary': trimmedSummary,
       if (trimmedNote != null && trimmedNote.isNotEmpty) 'note': trimmedNote,
+      if (metadata != null && metadata!.isNotEmpty) 'metadata': metadata,
     };
+    if (steps.isNotEmpty) {
+      payload['steps'] = steps
+          .map((item) => _mapApprovalStep(item))
+          .toList(growable: false);
+    }
+    return payload;
   }
 }
 
@@ -236,3 +277,14 @@ String _formatNaiveDate(DateTime value) {
   final day = value.day.toString().padLeft(2, '0');
   return '$year-$month-$day';
 }
+
+String _formatIsoUtc(DateTime value) => value.toUtc().toIso8601String();
+
+Map<String, dynamic> _mapApprovalStep(ApprovalStepAssignmentItem item) {
+  final trimmedNote = item.note?.trim();
+  return {
+    'step_order': item.stepOrder,
+    'approver_id': item.approverId,
+    if (trimmedNote != null && trimmedNote.isNotEmpty) 'note': trimmedNote,
+  };
+}