Add npm package with WASM + TypeScript wrapper

[MickeyShnaiderman-RecoLabs]

Summary

Ship gnata WASM as an npm package (gnata) for browser consumption.

• npm/: TypeScript package source with jsonata()-compatible API
• scripts/build-npm.sh: Builds gnata.wasm + copies wasm_exec.js from Go toolchain, then compiles TypeScript
• .github/workflows/publish-npm.yml: Publishes to npm on tag push via OIDC Trusted Publishing (no long-lived tokens, automatic provenance attestations)

The package:

• Lazy-loads gnata.wasm + wasm_exec.js on first evaluation
• Falls back to jsonata npm (optional peer dep) when WASM is unavailable
• Exposes configure() for custom asset URLs
• Correctly preserves null vs undefined semantics through the Go WASM boundary

How consumers use it

npm install gnata

import { jsonata } from 'gnata';
const result = await jsonata('Account.Order.Price').evaluate(data);

Assets (gnata.wasm, wasm_exec.js) need to be served at /wasm/ — use rspack/webpack CopyPlugin or similar.

Test plan

• scripts/build-npm.sh builds WASM + TypeScript successfully
• TypeScript compiles with tsc --noEmit
• First manual npm publish from local machine
• Configure Trusted Publishing on npmjs.com
• Verify tag-triggered CI publish works