feat: implement user-scoped receipt aliases with global fallback; enhance alias management in admin panel

flutter/lib/features/admin/data/admin_repository.dart

@@ -9,6 +9,7 @@ import '../domain/admin_category_node.dart';
 import '../domain/admin_product.dart';
 import '../domain/ai_model_info.dart';
 import '../domain/pending_product.dart';
+import '../domain/receipt_alias.dart';
 import '../domain/user_admin.dart';
 
 final adminRepositoryProvider = Provider<AdminRepository>((ref) {
@@ -213,6 +214,21 @@ class AdminRepository {
         'targetProductId': targetProductId,
       });
 
+  Future<Map<String, dynamic>> previewMerge({
+    required int sourceProductId,
+    required int targetProductId,
+  }) async {
+    final token = await _token();
+    final data = await guardedApiCall(
+      _ref,
+      () => _apiClient.getJson(
+        ProductApiPaths.mergePreview(sourceProductId, targetProductId),
+        token: token,
+      ),
+    );
+    return Map<String, dynamic>.from(data as Map);
+  }
+
   Future<List<AdminAiCategorizeResult>> aiCategorizeBulk({
     List<int>? productIds,
   }) async {
@@ -246,4 +262,23 @@ class AdminRepository {
   /// OBS: endpointen /ai/models kräver autentisering.
   Future<List<AiModelInfo>> listAiModels() =>
       _getList(AiApiPaths.models, AiModelInfo.fromJson);
+
+  // ── Kvittoalias (admin/global fallback) ───────────────────────────────────
+
+  Future<List<ReceiptAlias>> listReceiptAliases() =>
+      _getList(ReceiptAliasApiPaths.list, ReceiptAlias.fromJson);
+
+  Future<void> upsertReceiptAlias({
+    required String receiptName,
+    required int productId,
+    bool isGlobal = false,
+  }) =>
+      _postVoid(ReceiptAliasApiPaths.list, {
+        'receiptName': receiptName,
+        'productId': productId,
+        'isGlobal': isGlobal,
+      });
+
+  Future<void> removeReceiptAlias(int id) =>
+      _deleteVoid(ReceiptAliasApiPaths.remove(id));
 }