feat: migrate to napi-rs v3 and update release workflow

[zastrowm]

Description

Updates the release workflow so that cutting a vX.Y.Z tag is the only release action needed, following the existing convention from strands-sdk.

Callouts:

• napi-rs v3 migration — napi/napi-derive upgraded to v3, CLI to @napi-rs/cli@^3.7.2
• Version derived from git tag — Manifests carry 0.0.0; .github/actions/stamp-version stamps the tag at build time
• OIDC trusted publishing — npm publish uses id-token: write (no NPM_TOKEN secret)
• Per-platform npm publish matrix — 4 platform packages publish independently (fail-fast: false) so that each are retriable independently. The main package is published following the platform specific items.
• Pre-publish safety gates — node-pack and python-inspect upload downloadable artifacts for local testing

Example workflow: https://github.com/zastrowm/shell/actions/runs/27622359408 (fails on release because we haven't set up publishing yet)

Related Issues

Addresses the release pipeline requirements from #1.

Documentation PR

N/A — CI/workflow changes only.

Type of Change

New feature

Testing

Validated end-to-end across 6 CI runs on a fork (zastrowm/shell, tags v0.2.0 through v0.2.6):

• All build, pack, and inspection jobs pass green
• Publish jobs fail as expected (no OIDC trusted publisher configured on the fork)
• Downloaded npm-packages artifact, published to a local Verdaccio registry, confirmed npm install @strands-agents/shell auto-resolves the correct platform optionalDependency
• Downloaded pypi-dist-bundle, installed via pip install --find-links, confirmed platform tag resolution picks the correct wheel
• Both Node and Python packages run successfully after install

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• I ran the relevant test suites for the bindings I touched (cargo test --workspace --all-targets, pytest tests/python, npm test)
• If I touched Rust, I ran cargo fmt and cargo clippy

Checklist

• I have read the CONTRIBUTING document
• I have reviewed and understand every line of code in this PR, including any generated by AI tools, and I can explain why it works
• My change is focused and reasonably small; I have split unrelated work into separate PRs
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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