feat: implement boxing module with three modes (one2one, one2many, many2one)

- Add BoxInfoResult/BoxSaveResult data classes and API methods to ApiService
- Create BoxingPage with mode switching, auto-fill rules, duplicate detection
- Create BoxingDetailPage for read-only box detail view
- Activate boxing module in HomePage navigation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/services/api_service.dart

@@ -25,6 +25,120 @@ class RegistrationResult {
       RegistrationResult(success: false, errorMessage: message);
 }
 
+// === 装箱模块数据类 ===
+
+/// 箱号内单个总排号明细
+class BoxItemData {
+  final String zongpaiNo;
+  final int quantity;
+
+  BoxItemData({required this.zongpaiNo, required this.quantity});
+
+  factory BoxItemData.fromJson(Map<String, dynamic> json) {
+    return BoxItemData(
+      zongpaiNo: json['zongpai_no'] as String,
+      quantity: json['quantity'] as int,
+    );
+  }
+}
+
+/// 箱号明细
+class BoxDetailData {
+  final int boxNo;
+  final List<BoxItemData> items;
+
+  BoxDetailData({required this.boxNo, required this.items});
+
+  factory BoxDetailData.fromJson(Map<String, dynamic> json) {
+    final items = (json['items'] as List<dynamic>?)
+            ?.map((i) => BoxItemData.fromJson(i as Map<String, dynamic>))
+            .toList() ??
+        [];
+    return BoxDetailData(boxNo: json['box_no'] as int, items: items);
+  }
+}
+
+/// 装箱信息查询结果
+class BoxInfoResult {
+  final bool success;
+  final String? errorMessage;
+  final String? zongpaiNo;
+  final String? paichanNo;
+  final int? quantity;
+  final List<BoxDetailData> existingBoxes;
+  final int maxBoxNo;
+  final int suggestedBoxNo;
+
+  BoxInfoResult({
+    required this.success,
+    this.errorMessage,
+    this.zongpaiNo,
+    this.paichanNo,
+    this.quantity,
+    this.existingBoxes = const [],
+    this.maxBoxNo = 0,
+    this.suggestedBoxNo = 1,
+  });
+
+  factory BoxInfoResult.ok(Map<String, dynamic> json) {
+    final boxes = (json['existing_boxes'] as List<dynamic>?)
+            ?.map((b) => BoxDetailData.fromJson(b as Map<String, dynamic>))
+            .toList() ??
+        [];
+    return BoxInfoResult(
+      success: true,
+      zongpaiNo: json['zongpai_no'] as String?,
+      paichanNo: json['paichan_no'] as String?,
+      quantity: json['quantity'] as int?,
+      existingBoxes: boxes,
+      maxBoxNo: json['max_box_no'] as int? ?? 0,
+      suggestedBoxNo: json['suggested_box_no'] as int? ?? 1,
+    );
+  }
+
+  factory BoxInfoResult.error(String message) {
+    return BoxInfoResult(success: false, errorMessage: message);
+  }
+}
+
+/// 装箱保存结果
+class BoxSaveResult {
+  final bool success;
+  final bool isDuplicate;
+  final String? errorMessage;
+  final String? paichanNo;
+  final int? boxNo;
+
+  BoxSaveResult({
+    required this.success,
+    this.isDuplicate = false,
+    this.errorMessage,
+    this.paichanNo,
+    this.boxNo,
+  });
+
+  factory BoxSaveResult.ok(Map<String, dynamic> json) {
+    return BoxSaveResult(
+      success: true,
+      paichanNo: json['paichan_no'] as String?,
+      boxNo: json['box_no'] as int?,
+    );
+  }
+
+  factory BoxSaveResult.duplicate(Map<String, dynamic> json) {
+    return BoxSaveResult(
+      success: false,
+      isDuplicate: true,
+      paichanNo: json['paichan_no'] as String?,
+      boxNo: json['box_no'] as int?,
+    );
+  }
+
+  factory BoxSaveResult.error(String message) {
+    return BoxSaveResult(success: false, errorMessage: message);
+  }
+}
+
 class ApiService {
   final http.Client _client;
   final Duration timeout;
@@ -71,6 +185,77 @@ class ApiService {
     }
   }
 
+  /// 查询装箱信息 — GET /CargoTrace/box/info
+  Future<BoxInfoResult> fetchBoxInfo({
+    required String baseUrl,
+    required String zongpaiNo,
+  }) async {
+    final uri = Uri.parse('$baseUrl/CargoTrace/box/info').replace(
+      queryParameters: {'zongpai_no': zongpaiNo},
+    );
+    try {
+      final response = await _client
+          .get(uri, headers: {'Content-Type': 'application/json'})
+          .timeout(timeout);
+
+      switch (response.statusCode) {
+        case 200:
+          final body = jsonDecode(response.body) as Map<String, dynamic>;
+          return BoxInfoResult.ok(body);
+        case 400:
+          return BoxInfoResult.error('无效的总排号格式');
+        case 404:
+          return BoxInfoResult.error('未找到该总排号对应的排产号信息');
+        default:
+          return BoxInfoResult.error('查询失败 (${response.statusCode})');
+      }
+    } catch (e) {
+      return BoxInfoResult.error('网络异常，请检查网络连接');
+    }
+  }
+
+  /// 保存装箱记录 — POST /CargoTrace/box
+  Future<BoxSaveResult> saveBoxRecord({
+    required String baseUrl,
+    required String zongpaiNo,
+    required int boxNo,
+    required int quantity,
+  }) async {
+    final uri = Uri.parse('$baseUrl/CargoTrace/box');
+    try {
+      final response = await _client
+          .post(
+            uri,
+            headers: {'Content-Type': 'application/json'},
+            body: jsonEncode({
+              'zongpai_no': zongpaiNo,
+              'box_no': boxNo,
+              'quantity': quantity,
+            }),
+          )
+          .timeout(timeout);
+
+      switch (response.statusCode) {
+        case 200:
+          final body = jsonDecode(response.body) as Map<String, dynamic>;
+          return BoxSaveResult.ok(body);
+        case 400:
+          final body = jsonDecode(response.body) as Map<String, dynamic>;
+          final msg = body['message']?.toString() ?? '请求参数错误';
+          return BoxSaveResult.error(msg);
+        case 409:
+          final body = jsonDecode(response.body) as Map<String, dynamic>;
+          return BoxSaveResult.duplicate(body);
+        case 404:
+          return BoxSaveResult.error('未找到该总排号对应的排产号信息');
+        default:
+          return BoxSaveResult.error('提交失败 (${response.statusCode})');
+      }
+    } catch (e) {
+      return BoxSaveResult.error('网络异常，请检查网络连接');
+    }
+  }
+
   /// Test connectivity by making a HEAD request to the base URL.
   Future<bool> testConnection(String baseUrl) async {
     try {