refactor(core): enhance SDK structure and documentation

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

tests/Feature/Sbp/ConfigTest.php

@@ -0,0 +1,30 @@
+<?php
+
+use Apoloz\AlfaBank\Sbp\SbpConnector;
+use Apoloz\AlfaBank\Sbp\Requests\GetQrCodeRequest;
+use Apoloz\AlfaBank\Sbp\Data\QrCodeRequestData;
+use Apoloz\AlfaBank\Core\AlfaConfig;
+use Saloon\Http\Faking\MockResponse;
+
+test('sbp connector uses injected config', function () {
+    $mockClient = new \Saloon\Http\Faking\MockClient([
+        GetQrCodeRequest::class => MockResponse::make(['payload' => 'https://test.qr'], 200),
+    ]);
+
+    $config = new AlfaConfig(
+        baseUrl: 'https://test.alfa',
+        certificatePath: __DIR__ . '/../../test_key.pem', // valid path
+        privateKeyPath: __DIR__ . '/../../test_key.pem',  // valid path
+    );
+
+    $connector = new SbpConnector($config, 'alias');
+    $connector->withMockClient($mockClient);
+
+    expect($connector->resolveBaseUrl())->toBe('https://test.alfa');
+
+    $response = $connector->send(new GetQrCodeRequest(
+        new QrCodeRequestData('term', '01', '100', 'purpose')
+    ));
+
+    expect($response->status())->toBe(200);
+});