승인 단계 삭제 복구 흐름 구현하고 API 정렬 문서 추가

lib/features/approvals/step/presentation/controllers/approval_step_controller.dart

@@ -158,4 +158,64 @@ class ApprovalStepController extends ChangeNotifier {
       notifyListeners();
     }
   }
+
+  /// 결재 단계를 삭제(비활성화)하고 목록 상태를 반영한다.
+  Future<bool> deleteStep(int id) async {
+    _isSaving = true;
+    _errorMessage = null;
+    notifyListeners();
+    try {
+      await _repository.delete(id);
+      if (_result != null) {
+        final items = _result!.items
+            .map((record) {
+              final stepId = record.step.id;
+              if (stepId != null && stepId == id) {
+                return record.copyWith(
+                  step: record.step.copyWith(isDeleted: true),
+                );
+              }
+              return record;
+            })
+            .toList(growable: false);
+        _result = _result!.copyWith(items: items);
+      }
+      return true;
+    } catch (e) {
+      _errorMessage = e.toString();
+      return false;
+    } finally {
+      _isSaving = false;
+      notifyListeners();
+    }
+  }
+
+  /// 삭제된 결재 단계를 복구하고 최신 데이터를 반환한다.
+  Future<ApprovalStepRecord?> restoreStep(int id) async {
+    _isSaving = true;
+    _errorMessage = null;
+    notifyListeners();
+    try {
+      final record = await _repository.restore(id);
+      if (_result != null) {
+        final items = _result!.items
+            .map((item) {
+              final stepId = item.step.id;
+              if (stepId != null && stepId == id) {
+                return record;
+              }
+              return item;
+            })
+            .toList(growable: false);
+        _result = _result!.copyWith(items: items);
+      }
+      return record;
+    } catch (e) {
+      _errorMessage = e.toString();
+      return null;
+    } finally {
+      _isSaving = false;
+      notifyListeners();
+    }
+  }
 }