Mirrors the pnpm-detection logic from plugin-ci.yaml. When a repo has
pnpm-lock.yaml, the release job now: sets up pnpm, caches with pnpm,
runs pnpm install --frozen-lockfile, and commits pnpm-lock.yaml (not
package-lock.json) in the release branch.
Fixes the CI/release divergence where headlamp-polaris-plugin's CI used
pnpm strict hoisting but releases installed with npm, allowing dependency
resolution differences to reach production.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
Hugh Hackman
a62d4181ee