docs: add x402 agent payment example with ASG Card

docs/examples/asgcard-x402-payment.js

@@ -0,0 +1,34 @@
+/**
+ * ASG Card x402 Payment Example
+  * 
+   * Demonstrates using the Stellar JS SDK with the x402 protocol
+    * to create and fund virtual MasterCard cards for AI agents.
+     * 
+      * Requirements:
+       *   npm install @asgcard/sdk @stellar/stellar-sdk
+        * 
+         * More info: https://asgcard.dev
+          */
+
+const { Keypair, Networks, TransactionBuilder, Operation, Asset } = require('@stellar/stellar-sdk');
+
+// Example: Create a Stellar keypair for agent wallet
+const agentKeypair = Keypair.random();
+console.log('Agent Public Key:', agentKeypair.publicKey());
+console.log('Agent Secret:', agentKeypair.secret());
+
+// The x402 protocol flow:
+// 1. Agent generates a Stellar keypair
+// 2. Agent funds the wallet with USDC (Stellar asset)
+// 3. Agent calls ASG Card API to create a virtual MasterCard
+// 4. Payment is verified on-chain via x402 payment header
+// 5. Agent receives card details (PAN, CVV, expiry)
+
+// For the complete agent-ready implementation, see:
+// https://github.com/ASGCompute/asgcard-public
+// https://www.npmjs.com/package/@asgcard/sdk
+
+console.log('\nTo set up an AI agent with payment capability:');
+console.log('  npx @asgcard/cli onboard -y');
+console.log('\nThis creates a Stellar wallet and configures the MCP server.');
+console.log('Your agent can then autonomously create and manage virtual cards.');