feat(shopinbit): add car request payload and invoice recovery to client

diff --git a/lib/services/shopinbit/src/client.dart b/lib/services/shopinbit/src/client.dart
index ad695e2..1ca8197 100644
--- a/lib/services/shopinbit/src/client.dart
+++ b/lib/services/shopinbit/src/client.dart
@@ -355,12 +355,14 @@ class ShopInBitClient {
 
   Future<ApiResponse<CarResearchInvoice>> createCarResearchInvoice({
     required Address billing,
+    CarResearchRequest? request,
   }) async {
     return _request(
       'POST',
       '/car-research/invoice',
       body: {
         'billing': billing.toJson(),
+        if (request != null) 'request': request.toJson(),
         if (_externalCustomerKey != null)
           'external_customer_key': _externalCustomerKey,
       },
@@ -368,6 +370,31 @@ class ShopInBitClient {
     );
   }
 
+  /// Unresolved car research invoices for the current partner/customer pair.
+  /// Used to recover a fee payment the user started but did not finish.
+  Future<ApiResponse<List<CarResearchCurrentInvoice>>>
+  getCurrentCarResearchInvoices() async {
+    return _requestRaw(
+      'GET',
+      '/car-research/invoices/current',
+      parse: (body) {
+        if (body.isEmpty) return <CarResearchCurrentInvoice>[];
+        final decoded = jsonDecode(body);
+        final list = decoded is List
+            ? decoded
+            : (decoded as Map<String, dynamic>)['invoices'] as List? ??
+                  const [];
+        return list
+            .map(
+              (e) => CarResearchCurrentInvoice.fromJson(
+                e as Map<String, dynamic>,
+              ),
+            )
+            .toList();
+      },
+    );
+  }
+
   Future<ApiResponse<Map<String, dynamic>>> getCarResearchInvoiceStatus(
     String invoiceId,
   ) async {
diff --git a/lib/services/shopinbit/src/models/car_research.dart b/lib/services/shopinbit/src/models/car_research.dart
index ea1eceb..e5bf15b 100644
--- a/lib/services/shopinbit/src/models/car_research.dart
+++ b/lib/services/shopinbit/src/models/car_research.dart
@@ -1,3 +1,82 @@
+/// Optional request payload cached with a car research fee invoice. When
+/// provided, the backend creates the real car research ticket itself after the
+/// fee is paid (the BTCPay webhook failsafe), so the client does not have to.
+class CarResearchRequest {
+  final String customerPseudonym;
+  final String comment;
+  final String deliveryCountry;
+
+  CarResearchRequest({
+    required this.customerPseudonym,
+    required this.comment,
+    required this.deliveryCountry,
+  });
+
+  Map<String, dynamic> toJson() => {
+    'customer_pseudonym': customerPseudonym,
+    'comment': comment,
+    'delivery_country': deliveryCountry,
+  };
+}
+
+/// An unresolved car research invoice returned by
+/// GET /car-research/invoices/current, used to recover a payment the user
+/// started but did not finish.
+class CarResearchCurrentInvoice {
+  final String invoiceId;
+  final String status;
+  final String? additional;
+  final DateTime? expiresAt;
+  final Map<String, String> paymentLinks;
+  final bool hasRequestPayload;
+  final DateTime? createdAt;
+
+  CarResearchCurrentInvoice({
+    required this.invoiceId,
+    required this.status,
+    required this.additional,
+    required this.expiresAt,
+    required this.paymentLinks,
+    required this.hasRequestPayload,
+    required this.createdAt,
+  });
+
+  factory CarResearchCurrentInvoice.fromJson(Map<String, dynamic> json) {
+    final linksRaw = json['payment_links'] as Map<String, dynamic>? ?? {};
+    final expiresRaw = json['expires_at'] as String?;
+    final createdRaw = json['created_at'] as String?;
+    return CarResearchCurrentInvoice(
+      invoiceId: json['invoice_id'] as String,
+      status: json['status'] as String? ?? '',
+      additional: json['additional'] as String?,
+      expiresAt: expiresRaw == null ? null : DateTime.tryParse(expiresRaw),
+      paymentLinks: linksRaw.map((k, v) => MapEntry(k, v as String)),
+      hasRequestPayload: json['has_request_payload'] as bool? ?? false,
+      createdAt: createdRaw == null ? null : DateTime.tryParse(createdRaw),
+    );
+  }
+}
+
+/// Whether a car research invoice status counts as paid/finalized per the
+/// ShopinBit 1.0.4 rules: Processing, Settled, or Expired with PaidLate. The
+/// extra lowercase values keep older concierge-style statuses working.
+bool carResearchIsFinalized(String? status, String? additional) {
+  final s = (status ?? '').toLowerCase().trim();
+  final a = (additional ?? '').toLowerCase().trim();
+  if (s == 'processing' || s == 'settled') return true;
+  if (s == 'expired' && a == 'paidlate') return true;
+  return const {
+    'paid',
+    'paid_over',
+    'paid_late',
+    'payment_processing',
+    'confirmed',
+    'complete',
+    'completed',
+    'finalized',
+  }.contains(s);
+}
+
 class CarResearchInvoice {
   final String btcpayInvoice;
   final DateTime expiresAt;