pnpm/action-setup@v4 ran at the repo root (uses: steps ignore
defaults.run.working-directory) where there is no package.json, so it couldn't
read the pnpm version → "No pnpm version specified". Use corepack (bundled with
node) in the install step, which reads each app's own packageManager — matching
the Dockerfiles. Verified in the runner's container: corepack enable + frozen
install succeeds for every app.
pnpm/action-setup ran with no version: `uses:` steps ignore
defaults.run.working-directory, so it executed at the repo root, which has no
package.json (per-app monorepo) → "No pnpm version specified". Pin version: 9
explicitly. Also drop setup-node's `cache: pnpm` — the act_runner cache server
isn't reachable from the DinD job containers, and the install is fast anyway.
Ronni Baslund