feat: add npm and PyPI distribution channels

[stephenc222]

Summary

• Adds hotspots wrapper package + 3 platform packages (@stephencollinstech/hotspots-linux-x64, @stephencollinstech/hotspots-darwin-arm64, @stephencollinstech/hotspots-win32-x64) for npm distribution
• Adds pyproject.toml for PyPI distribution via maturin as hotspots-cli (binary stays hotspots)
• Adds publish-npm and publish-pypi jobs to release.yml, running after build-binaries

Test plan

• Add NPM_TOKEN and PYPI_TOKEN to GitHub Actions secrets (already done)
• Trigger a dry-run release to verify workflow jobs appear and pass quality gates
• On first real release, confirm hotspots appears on npmjs.com and hotspots-cli appears on pypi.org
• Verify npm install -g hotspots and pip install hotspots-cli install a working binary

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