test(monetization): MonetizationState 및 복귀 보상 테스트 추가

- MonetizationState 23개 테스트 (버프 활성/만료, 유료/무료 분기)
- ReturnRewardsService 14개 테스트 (보상 계산, 2배 시간, 포맷팅)

test/core/model/monetization_state_test.dart

@@ -0,0 +1,221 @@
+import 'package:asciineverdie/src/core/model/monetization_state.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('MonetizationState', () {
+    // =========================================================================
+    // initial 팩토리(factory) 테스트
+    // =========================================================================
+
+    group('initial', () {
+      test('무료 사용자(free user) 기본 상태', () {
+        final state = MonetizationState.initial();
+
+        expect(state.undoRemaining, equals(1));
+        expect(state.adRemovalPurchased, isFalse);
+        expect(state.rollsRemaining, equals(5));
+        expect(state.pendingChests, equals(0));
+        expect(state.rollHistory, isNull);
+      });
+
+      test('유료 사용자(paid user) 기본 상태', () {
+        final state = MonetizationState.initial(isPaidUser: true);
+
+        expect(state.undoRemaining, equals(3));
+        expect(state.adRemovalPurchased, isTrue);
+        expect(state.rollsRemaining, equals(5));
+        expect(state.pendingChests, equals(0));
+      });
+    });
+
+    // =========================================================================
+    // isPaidUser / isFreeUser 게터(getter) 테스트
+    // =========================================================================
+
+    group('isPaidUser / isFreeUser', () {
+      test('광고 제거 구매 시 isPaidUser true', () {
+        final state = MonetizationState.initial(isPaidUser: true);
+
+        expect(state.isPaidUser, isTrue);
+        expect(state.isFreeUser, isFalse);
+      });
+
+      test('광고 제거 미구매 시 isFreeUser true', () {
+        final state = MonetizationState.initial();
+
+        expect(state.isPaidUser, isFalse);
+        expect(state.isFreeUser, isTrue);
+      });
+    });
+
+    // =========================================================================
+    // isAutoReviveActive 테스트
+    // =========================================================================
+
+    group('isAutoReviveActive', () {
+      test('autoReviveEndMs가 null이면 false 반환', () {
+        final state = MonetizationState.initial();
+
+        expect(state.isAutoReviveActive(1000), isFalse);
+      });
+
+      test('elapsedMs가 종료 시점 이내면 true 반환', () {
+        final state = MonetizationState.initial().copyWith(
+          autoReviveEndMs: 5000,
+        );
+
+        expect(state.isAutoReviveActive(3000), isTrue);
+      });
+
+      test('elapsedMs가 종료 시점을 초과하면 false 반환', () {
+        final state = MonetizationState.initial().copyWith(
+          autoReviveEndMs: 5000,
+        );
+
+        expect(state.isAutoReviveActive(6000), isFalse);
+      });
+
+      test('elapsedMs가 종료 시점과 정확히 같으면 false 반환 (경계값)', () {
+        final state = MonetizationState.initial().copyWith(
+          autoReviveEndMs: 5000,
+        );
+
+        expect(state.isAutoReviveActive(5000), isFalse);
+      });
+    });
+
+    // =========================================================================
+    // isSpeedBoostActive 테스트
+    // =========================================================================
+
+    group('isSpeedBoostActive', () {
+      test('유료 사용자는 항상 true 반환', () {
+        final state = MonetizationState.initial(isPaidUser: true);
+
+        // speedBoostEndMs가 null이어도 유료 사용자는 항상 활성
+        expect(state.isSpeedBoostActive(0), isTrue);
+        expect(state.isSpeedBoostActive(999999), isTrue);
+      });
+
+      test('무료 사용자 - 종료 시점 이내면 true 반환', () {
+        final state = MonetizationState.initial().copyWith(
+          speedBoostEndMs: 10000,
+        );
+
+        expect(state.isSpeedBoostActive(5000), isTrue);
+      });
+
+      test('무료 사용자 - 종료 시점 초과 시 false 반환', () {
+        final state = MonetizationState.initial().copyWith(
+          speedBoostEndMs: 10000,
+        );
+
+        expect(state.isSpeedBoostActive(15000), isFalse);
+      });
+
+      test('무료 사용자 - speedBoostEndMs가 null이면 false 반환', () {
+        final state = MonetizationState.initial();
+
+        expect(state.isSpeedBoostActive(1000), isFalse);
+      });
+    });
+
+    // =========================================================================
+    // isLuckyCharmActive 테스트
+    // =========================================================================
+
+    group('isLuckyCharmActive', () {
+      test('종료 시점 이내면 true 반환', () {
+        final state = MonetizationState.initial().copyWith(
+          luckyCharmEndMs: 8000,
+        );
+
+        expect(state.isLuckyCharmActive(4000), isTrue);
+      });
+
+      test('종료 시점 초과 시 false 반환', () {
+        final state = MonetizationState.initial().copyWith(
+          luckyCharmEndMs: 8000,
+        );
+
+        expect(state.isLuckyCharmActive(9000), isFalse);
+      });
+
+      test('luckyCharmEndMs가 null이면 false 반환', () {
+        final state = MonetizationState.initial();
+
+        expect(state.isLuckyCharmActive(1000), isFalse);
+      });
+    });
+
+    // =========================================================================
+    // canRoll 테스트
+    // =========================================================================
+
+    group('canRoll', () {
+      test('rollsRemaining > 0이면 true 반환', () {
+        final state = MonetizationState.initial(); // rollsRemaining=5
+
+        expect(state.canRoll, isTrue);
+      });
+
+      test('rollsRemaining == 0이면 false 반환', () {
+        final state = MonetizationState.initial().copyWith(rollsRemaining: 0);
+
+        expect(state.canRoll, isFalse);
+      });
+    });
+
+    // =========================================================================
+    // maxChests 테스트
+    // =========================================================================
+
+    group('maxChests', () {
+      test('유료 사용자는 최대 10개', () {
+        final state = MonetizationState.initial(isPaidUser: true);
+
+        expect(state.maxChests, equals(10));
+      });
+
+      test('무료 사용자는 최대 5개', () {
+        final state = MonetizationState.initial();
+
+        expect(state.maxChests, equals(5));
+      });
+    });
+
+    // =========================================================================
+    // isChestsFull 테스트
+    // =========================================================================
+
+    group('isChestsFull', () {
+      test('무료 사용자 - pendingChests가 maxChests 이상이면 true', () {
+        final state = MonetizationState.initial().copyWith(pendingChests: 5);
+
+        expect(state.isChestsFull, isTrue);
+      });
+
+      test('무료 사용자 - pendingChests가 maxChests 미만이면 false', () {
+        final state = MonetizationState.initial().copyWith(pendingChests: 3);
+
+        expect(state.isChestsFull, isFalse);
+      });
+
+      test('유료 사용자 - pendingChests가 maxChests 이상이면 true', () {
+        final state = MonetizationState.initial(
+          isPaidUser: true,
+        ).copyWith(pendingChests: 10);
+
+        expect(state.isChestsFull, isTrue);
+      });
+
+      test('유료 사용자 - pendingChests가 maxChests 초과해도 true', () {
+        final state = MonetizationState.initial(
+          isPaidUser: true,
+        ).copyWith(pendingChests: 12);
+
+        expect(state.isChestsFull, isTrue);
+      });
+    });
+  });
+}