refactor(shopinbit): drop the single-flight ticket/invoice fetch wrappers

diff --git a/lib/services/shopinbit/shopinbit_service.dart b/lib/services/shopinbit/shopinbit_service.dart
index 107da76..4a7fe79 100644
--- a/lib/services/shopinbit/shopinbit_service.dart
+++ b/lib/services/shopinbit/shopinbit_service.dart
@@ -22,60 +22,9 @@ class ShopInBitService {
 
   final Map<int, Completer<void>> _inFlight = {};
 
-  // Combine concurrent list/invoice fetches the same way _refreshRef does, so
-  // overlapping refreshes (e.g. tickets view refresh racing a post-action one)
-  // share a single round-trip instead of each hitting the API.
-  Completer<ApiResponse<List<TicketRef>>>? _ticketsInFlight;
-  String? _ticketsInFlightKey;
-  Completer<ApiResponse<List<CarResearchCurrentInvoice>>>? _carInvoicesInFlight;
-
-  /// Combined by-customer ticket list fetch.  Concurrent calls for the same
-  /// key await the same in-flight request.
-  Future<ApiResponse<List<TicketRef>>> _ticketsByCustomer(String key) {
-    final Completer<ApiResponse<List<TicketRef>>>? pending = _ticketsInFlight;
-    if (pending != null && _ticketsInFlightKey == key) {
-      return pending.future;
-    }
-    final Completer<ApiResponse<List<TicketRef>>> completer = Completer();
-    _ticketsInFlight = completer;
-    _ticketsInFlightKey = key;
-    unawaited(
-      client
-          .getTicketsByCustomer(key)
-          .then(completer.complete, onError: completer.completeError)
-          .whenComplete(() {
-            if (_ticketsInFlight == completer) {
-              _ticketsInFlight = null;
-              _ticketsInFlightKey = null;
-            }
-          }),
-    );
-    return completer.future;
-  }
-
-  /// Combined wrapper around the current car research invoices fetch.  The
-  /// tickets view calls this on every refresh, so dedup keeps overlapping
-  /// refreshes from each firing their own request.
+  /// Current still-payable car research invoices for the active customer key.
   Future<ApiResponse<List<CarResearchCurrentInvoice>>>
-  getCurrentCarResearchInvoices() {
-    final Completer<ApiResponse<List<CarResearchCurrentInvoice>>>? pending =
-        _carInvoicesInFlight;
-    if (pending != null) return pending.future;
-    final Completer<ApiResponse<List<CarResearchCurrentInvoice>>> completer =
-        Completer();
-    _carInvoicesInFlight = completer;
-    unawaited(
-      client
-          .getCurrentCarResearchInvoices()
-          .then(completer.complete, onError: completer.completeError)
-          .whenComplete(() {
-            if (_carInvoicesInFlight == completer) {
-              _carInvoicesInFlight = null;
-            }
-          }),
-    );
-    return completer.future;
-  }
+  getCurrentCarResearchInvoices() => client.getCurrentCarResearchInvoices();
 
   // -- Customer key --
 
@@ -115,7 +64,9 @@ class ShopInBitService {
   /// New tickets are hydrated and inserted; existing tickets are patched.
   Future<void> refreshAll() async {
     final String key = await ensureCustomerKey();
-    final ApiResponse<List<TicketRef>> resp = await _ticketsByCustomer(key);
+    final ApiResponse<List<TicketRef>> resp = await client.getTicketsByCustomer(
+      key,
+    );
     if (resp.hasError || resp.value == null) {
       Logging.instance.w(
         "ShopInBitService.refreshAll: failed to fetch ticket list",