pnpm CI on GitHub Actions

pnpm install is fast locally but slow in CI.

Why it happens

The pnpm content-addressed store lives outside the project and is not cached, so every package downloads again.

What to change

1. Cache the pnpm store path returned by pnpm store path
2. Install with --frozen-lockfile for reproducibility
3. Use the store cache rather than caching node_modules — it deduplicates across workspaces

pnpm on runnerhut

jobs:
  test:
    runs-on: runnerhut-4vcpu-ubuntu-2404
    steps:
      - uses: actions/checkout@v4
      - uses: pnpm/action-setup@v4
      - uses: actions/setup-node@v4
        with: { node-version: 22, cache: pnpm }
      - run: pnpm install --frozen-lockfile
      - run: pnpm test

The only runnerhut-specific line is `runs-on: runnerhut-4vcpu-ubuntu-2404`. Everything else is standard GitHub Actions — the same actions, the same secrets and the same permissions model you use today.