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/pages/home_page.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:pad_scanner/services/app_config_service.dart';
 import 'package:pad_scanner/pages/settings_page.dart';
 import 'package:pad_scanner/pages/registration_page.dart';
+import 'package:pad_scanner/pages/boxing_page.dart';
 import 'package:pad_scanner/services/api_service.dart';
 
 /// Module type enum for each available feature card
@@ -60,8 +61,8 @@ class _HomePageState extends State<HomePage> {
       icon: Icons.view_list_outlined,
       title: '装箱编号',
       description: '查询箱号、录入装箱明细',
-      status: ModuleStatus.developing,
-      version: null,
+      status: ModuleStatus.online,
+      version: 'v1.0',
       route: '/boxing',
     ),
     FeatureCard(
@@ -127,11 +128,7 @@ class _HomePageState extends State<HomePage> {
         targetPage = const RegistrationPage();
         break;
       case ModuleType.boxing:
-        //TODO: Implement boxing page
-        targetPage = Scaffold(
-          appBar: AppBar(title: const Text('装箱编号')),
-          body: const Center(child: Text('开发中')),
-        );
+        targetPage = const BoxingPage();
         break;
       case ModuleType.shelfQuery:
         return; // 规划中，不导航