feat(android): add attachment pending banner on boxing page

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

lib/services/api_service.dart

@@ -195,6 +195,7 @@ class BoxInfoResult {
   final List<BoxDetailData> existingBoxes;
   final int maxBoxNo;
   final int suggestedBoxNo;
+  final Map<String, dynamic>? attachmentSummary;
 
   BoxInfoResult({
     required this.success,
@@ -207,6 +208,7 @@ class BoxInfoResult {
     this.existingBoxes = const [],
     this.maxBoxNo = 0,
     this.suggestedBoxNo = 1,
+    this.attachmentSummary,
   });
 
   factory BoxInfoResult.ok(Map<String, dynamic> json) {
@@ -232,6 +234,7 @@ class BoxInfoResult {
       existingBoxes: boxes,
       maxBoxNo: json['max_box_no'] as int? ?? 0,
       suggestedBoxNo: json['suggested_box_no'] as int? ?? 1,
+      attachmentSummary: json['attachment_summary'] as Map<String, dynamic>?,
     );
   }