feat: Add QR code display for wallet addresses in x402 commands

[MQ37]

Summary

This PR adds QR code generation and display functionality to the x402 CLI commands, allowing users to easily scan and fund their wallets directly from the terminal.

Key Changes

• Added qrcode-terminal dependency to generate QR codes in the terminal
• Implemented generateQrCode() helper function that wraps the qrcode-terminal library with Promise-based API
• Implemented printAddressQrCode() function to display formatted QR codes with proper indentation and labels
• Integrated QR code display into three x402 commands:
  • x402 init: Shows QR code after wallet creation
  • x402 import: Shows QR code after wallet import
  • x402 info: Shows QR code when displaying wallet information
• Updated CHANGELOG.md to document the new feature

Implementation Details

• QR codes are generated using the "small" (half-block) mode for compact terminal display
• Each QR code is prefixed with "Scan to fund this wallet:" label
• Output is properly indented (2 spaces) to align with surrounding CLI output
• The implementation uses async/await pattern for consistency with the rest of the codebase

https://claude.ai/code/session_018sHtRmQ1eguqqLZxzDzxK9