feat: add payment

lib/core/payment/bazaar_payment_gateway.dart

@@ -0,0 +1,46 @@
+import 'package:flutter_poolakey/flutter_poolakey.dart';
+
+import '../config.dart';
+import 'payment_gateway.dart';
+
+/// پرداختِ درون‌برنامه‌ایِ کافه‌بازار (Poolakey) — flavorِ `bazaar`.
+class BazaarPaymentGateway implements PaymentGateway {
+  bool _connected = false;
+
+  @override
+  String get store => 'bazaar';
+
+  @override
+  Future<void> connect() async {
+    if (_connected) return;
+    await FlutterPoolakey.connect(
+      AppConfig.bazaarRsaKey,
+      onDisconnected: () => _connected = false,
+    );
+    _connected = true;
+  }
+
+  @override
+  Future<PurchaseResult> purchase(String productSku) async {
+    try {
+      await connect();
+      final info = await FlutterPoolakey.purchase(
+        productSku,
+        payload: 'hakemsho',
+      );
+      if (info.purchaseToken.isEmpty) {
+        return const PurchaseResult.failure();
+      }
+      return PurchaseResult.success(
+        token: info.purchaseToken,
+        purchaseData: info.originalJson,
+        signature: info.dataSignature,
+        // کالای مصرفی باید مصرف شود تا خریدِ مجدد ممکن باشد.
+        onConfirmed: () => FlutterPoolakey.consume(info.purchaseToken),
+      );
+    } catch (_) {
+      // کنسل‌شدن یا خطای بازار ⇒ شکستِ خرید.
+      return const PurchaseResult.failure();
+    }
+  }
+}