refactor(core): enhance SDK structure and documentation

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

examples/03_sandbox_init.php

@@ -0,0 +1,55 @@
+<?php
+
+require_once __DIR__ . '/../vendor/autoload.php';
+
+use Apoloz\AlfaBank\AlfaBank;
+use Apoloz\AlfaBank\Enums\Environment;
+
+/**
+ * This example shows how to initialize the SDK with the Sandbox files provided by the bank.
+ * 
+ * IMPORTANT: You must first convert the .pfx file to .pem format using OpenSSL:
+ * 
+ * 1. Extract signing key: 
+ *    openssl pkcs12 -in certificate_for_requests_sign_with_password_1234.pfx -nocerts -out signing_key.pem -nodes -password pass:1234
+ * 
+ * 2. Extract signing certificate:
+ *    openssl pkcs12 -in certificate_for_requests_sign_with_password_1234.pfx -clcerts -nokeys -out signing_cert.pem -password pass:1234
+ * 
+ * 3. Ensure transport certs are in PEM format if they aren't already.
+ */
+
+// --- 1. BaaS / Main API Initialization ---
+$baas = AlfaBank::baas(
+    // Transport (mTLS) - use the sandbox_cert/key files
+    certificatePath: __DIR__ . '/certs/sandbox_cert_2026.cer', 
+    privateKeyPath: __DIR__ . '/certs/sandbox_key_2026.key',
+    
+    // Signing (Business Logic) - use the extracted PEM files from PFX
+    signingCertificatePath: __DIR__ . '/certs/signing_cert.pem',
+    signingPrivateKeyPath: __DIR__ . '/certs/signing_key.pem',
+    
+    environment: Environment::SANDBOX,
+    caBundlePath: __DIR__ . '/certs/apica_2022_chain.cer' // Trust chain
+);
+
+echo "BaaS Connector Initialized.\n";
+
+
+// --- 2. SBP (Faster Payments) Initialization ---
+$sbp = AlfaBank::sbp(
+    // SBP usually uses its own mTLS pair found in the sbp_payout/mtls folder
+    certificatePath: __DIR__ . '/certs/sbp_payout/mtls/9728109955_test_mtls.crt',
+    privateKeyPath: __DIR__ . '/certs/sbp_payout/mtls/9728109955_test_mtls.key',
+    
+    // Terminal ID from terminal_num.txt
+    keyNameAlias: '9728109955', 
+    
+    environment: Environment::SANDBOX,
+    caBundlePath: __DIR__ . '/certs/sbp_payout/sandbox_root/root-ca-test.crt'
+);
+
+echo "SBP Connector Initialized.\n";
+
+// Now you can use $baas->login(...) or $sbp->send(...)
+