script for signing a Bitcoin transaction

[timkon99]

Summary

Added a new example script example-sign-transaction.js under /src/
to demonstrate how to sign a basic Bitcoin transaction using bitcoinjs-lib.

Details

• Utilizes Psbt for transaction construction and signing.
• Generates a random key pair using ECPairFactory(tinysecp256k1).
• Uses Testnet for safety and demonstration purposes.
• Includes console outputs for both signed TX hex and sender address.

Motivation

While the README and docs describe the PSBT API, there was no minimal,
ready-to-run code example showing the full signing process.
This addition should help developers quickly understand
how to build and sign transactions in a test environment.

Notes

• Compatible with Node.js LTS (ESM format)
• Verified on bitcoinjs-lib v7.0.0