feat: handle off-shelf registration results

lib/services/api_service.dart

@@ -5,23 +5,41 @@ import 'package:http/http.dart' as http;
 class RegistrationResult {
   final bool success;
   final bool isDuplicate;
+  final bool isAlreadyOffShelf;
+  final bool isOffShelfSuccess;
   final String? errorMessage;
   final Map<String, dynamic>? duplicateInfo;
+  final Map<String, dynamic>? conflictInfo;
 
   RegistrationResult({
     required this.success,
     this.isDuplicate = false,
+    this.isAlreadyOffShelf = false,
+    this.isOffShelfSuccess = false,
     this.errorMessage,
     this.duplicateInfo,
+    this.conflictInfo,
   });
 
   factory RegistrationResult.ok() => RegistrationResult(success: true);
 
+  factory RegistrationResult.offShelfSuccess() =>
+      RegistrationResult(success: true, isOffShelfSuccess: true);
+
   factory RegistrationResult.duplicate(Map<String, dynamic> info) =>
       RegistrationResult(
         success: false,
         isDuplicate: true,
         duplicateInfo: info,
+        conflictInfo: info,
+      );
+
+  factory RegistrationResult.alreadyOffShelf(Map<String, dynamic> info) =>
+      RegistrationResult(
+        success: false,
+        isAlreadyOffShelf: true,
+        errorMessage: info['message']?.toString() ?? '该总排号已下架至转运区域，不可重新上架',
+        conflictInfo: info,
       );
 
   factory RegistrationResult.error(String message) =>
@@ -228,6 +246,10 @@ class ApiService {
 
       switch (response.statusCode) {
         case 200:
+          final body = jsonDecode(response.body) as Map<String, dynamic>;
+          if (body['previous_location'] != null) {
+            return RegistrationResult.offShelfSuccess();
+          }
           return RegistrationResult.ok();
         case 400:
           final body = jsonDecode(response.body) as Map<String, dynamic>;
@@ -235,7 +257,15 @@ class ApiService {
           return RegistrationResult.error(msg);
         case 409:
           final body = jsonDecode(response.body) as Map<String, dynamic>;
-          return RegistrationResult.duplicate(body);
+          final errorCode = body['error_code']?.toString();
+          if (errorCode == 'DUPLICATE_LOCATION') {
+            return RegistrationResult.duplicate(body);
+          }
+          if (errorCode == 'ALREADY_OFF_SHELF') {
+            return RegistrationResult.alreadyOffShelf(body);
+          }
+          final msg = body['message']?.toString() ?? '提交失败';
+          return RegistrationResult.error(msg);
         default:
           final body = jsonDecode(response.body) as Map<String, dynamic>;
           final msg =