Find workspace packages from both pnpm-workspace.yaml and package.json

[Huldoser]

What changed

trigger.dev keeps an old workspaces list in package.json next to its pnpm-workspace.yaml, and the scan read only the old list, so @internal/testcontainers was reported as "not a local file, a path alias or a workspace package". pnpm reads only pnpm-workspace.yaml, and npm, Yarn and Bun only package.json, so packages from both lists are found now.

No change on the corpus.

Checklist

• Tests cover the change, and npm run coverage reports 100%.
• The docs describe the change: the guide or reference pages, the README, or the TSDoc of exported functions.
• No docs change is needed.
• A changeset describes the change for users (npm run changeset), or the change does not affect them.