[v0.1 W5] Distribution wiring (npm shim + maturin + GitHub Actions release)

[liam-ai-reality]

Week 5 of v0.1 implementation. References: design.md §9.

• Replace npm placeholder with biome-style shim:
  • npm/klasp/package.json with optionalDependencies for 5 platform sub-packages
  • npm/klasp/bin/klasp.js (~20 lines using require.resolve)
  • 5 per-platform stub package.json files (@klasp-dev/klasp-darwin-arm64, etc.) with os/cpu fields
• Replace PyPI placeholder with maturin: switch pypi/pyproject.toml to [build-system] build-backend = "maturin", [tool.maturin] bindings = "bin". Remove the Hatchling stub.
• .github/workflows/release.yml — on tag push:
  1. matrix build per-platform binary, upload artifact
  2. publish job: download all artifacts, stage into npm sub-packages and PyPI wheel directories
  3. publish order: per-platform npm packages → main npm package → PyPI wheels → cargo publish → GitHub Release
• Tag v0.1.0-rc.1, verify cargo install klasp@0.1.0-rc.1, npm i -g @klasp-dev/klasp@0.1.0-rc.1, pip install klasp==0.1.0rc1 all resolve cleanly from a fresh machine