remove tiny-secp256k1 from xpub-lib dependencies, add initEccLib function, require for taproot

[turkycat]

Some projects, like vite-based web applications, have issues with tiny-secp256k1 v2 and up being included in the dependency tree since this relies on web assembly (wasm) dependencies. Wasm dependencies must be imported asynchronously which makes use of xpub-lib difficult in these environments.

This change models bitcoinjs-lib and requires the ECC library to be initialized before use.

[Copilot]

Pull Request Overview

This PR removes the direct dependency on tiny‑secp256k1 from xpub‑lib and introduces an explicit initialization function for the ECC library to support asynchronous WASM import environments, similar to bitcoinjs‑lib’s handling.

• Removed the direct import and initialization of tiny‑secp256k1 from xpub‑lib.
• Added an initEccLib function in xpub‑lib to allow consumers to initialize the ECC library as needed.
• Updated xpub‑cli to import and initialize the ECC library before using taproot functionality.

Reviewed Changes

Copilot reviewed 2 out of 4 changed files in this pull request and generated 1 comment.

File	Description
packages/xpub-lib/src/derivation.js	Removed direct dependency on tiny‑secp256k1 and added initEccLib.
packages/xpub-cli/src/xpub.js	Updated to call initEccLib with an imported instance of tiny‑secp256k1.

Files not reviewed (2)

• packages/xpub-cli/package.json: Language not supported
• packages/xpub-lib/package.json: Language not supported