NPM release workflow

[johnpmitsch]

Note

Medium Risk
Changes the release trigger and adds a new npm publishing workflow, which can affect artifact generation and package publishing if tags/releases or required binaries are misconfigured.

Overview
Adds a new GitHub Actions workflow (publish-npm.yml) to manually publish @quicknode/sdk (main package + per-platform napi subpackages) by downloading .node binaries from a specified GitHub release tag, verifying required platforms, running napi prepublish, and publishing to npm using an NPM_TOKEN.

Updates the existing release.yml workflow to trigger on GitHub release publish (instead of tag push) and to attach CI-built artifacts to the published release via tag_name: ${{ github.event.release.tag_name }}. Also renames the Node package from @quicknode/sdk-next to @quicknode/sdk, adds the macOS arm64 target to the napi target list, updates the browser shim error message, and documents the new npm release flow in README.md.

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