feat: integrate PaymentSDKCardApproval and update SDK dependencies

- Upgraded PayTabs SDK to version 6.6.5 in build.gradle.
- Added PaymentSDKCardApproval handling in FlutterPaytabsBridgePlugin.java for enhanced card approval functionality.
- Refactored payment logic in main.dart for improved readability and added support for card approval.
- Updated dependencies in pubspec.lock, including leak_tracker, material_color_utilities, meta, and test_api.
- Introduced PaymentSDKCardApproval.dart to manage card approval details like validation URL and bin length.

android/build.gradle

@@ -41,5 +41,5 @@ android {
 }
 
 dependencies {
-    implementation 'com.paytabs:payment-sdk:6.6.4'
+    implementation 'com.paytabs:payment-sdk:6.6.5'
 }

android/src/main/java/com/paymentsdk/flutter_paymentsdk_bridge/FlutterPaytabsBridgePlugin.java

@@ -20,6 +20,7 @@
 import com.payment.paymentsdk.integrationmodels.PaymentSDKQueryConfiguration;
 import com.payment.paymentsdk.integrationmodels.PaymentSdkApms;
 import com.payment.paymentsdk.integrationmodels.PaymentSdkBillingDetails;
+import com.payment.paymentsdk.integrationmodels.PaymentSdkCardApproval;
 import com.payment.paymentsdk.integrationmodels.PaymentSdkCardDiscount;
 import com.payment.paymentsdk.integrationmodels.PaymentSdkConfigurationDetails;
 import com.payment.paymentsdk.integrationmodels.PaymentSdkError;
@@ -379,6 +380,7 @@ private PaymentSdkConfigurationDetails getPaymentSdkConfigurationDetails(JSONObj
                 .isDigitalProduct(paymentDetails.optBoolean("pt_is_digital_product"))
                 .setPaymentExpiry(paymentScreenExpiry)
                 .setMetadata(getMetadata())
+                .setCardApproval(getCardApproval(paymentDetails))
                 .setCardDiscount(paymentSdkCardDiscounts).build();
     }
 
@@ -411,6 +413,22 @@ private static List<PaymentSdkCardDiscount> getPaymentSdkCardDiscounts(JSONObjec
         return paymentSdkCardDiscounts;
     }
 
+    /**
+     * Retrieves the card approval details from the provided JSON object.
+     *
+     * @param paymentDetails The JSON object containing payment details.
+     * @return A PaymentSdkCardApproval object containing the card approval details, or null if not present.
+     */
+    private static PaymentSdkCardApproval getCardApproval(JSONObject paymentDetails) {
+        JSONObject cardApproval = paymentDetails.optJSONObject("pt_card_approval");
+        if (cardApproval == null) return null;
+        return new PaymentSdkCardApproval(
+                cardApproval.optString("pt_validation_url"),
+                cardApproval.optInt("pt_bin_length"),
+                cardApproval.optBoolean("pt_block_if_no_response")
+        );
+    }
+
     public static String optString(JSONObject json, String key) {
         if (json.isNull(key)) return "";
         else return json.optString(key, null);