pnpm: Environment secrets exfiltrated via env-placeholder expansion in proxy settings read from an untrusted pnpm-workspace.yaml

## Summary pnpm expands `${VAR}` environment placeholders in the `httpProxy` / `httpsProxy` / `noProxy` settings read from a project's `pnpm-workspace.yaml`. Because a project manifest is repository-controlled, a malicious repository that a victim merely clones and runs `pnpm install` in can route all install traffic through an attacker proxy whose hostname or userinfo embeds — and thereby exfiltrates — an environment secret such as `NPM_TOKEN` or `GITHUB_TOKEN`. This bypasses a trust boundary pnpm deliberately enforces: env-placeholder expansion of request-destination settings is already suppressed for `registry`, `pnprServer`, `registries` and `namedRegistries` when they come from an untrusted project manifest, and the sibling `.npmrc` reader already classifies the proxy keys as request destinations. The manifest-side guard set simply omitted them. ## Impact An attacker who controls only the contents of a repository's `pnpm-workspace.yaml` — a public repo, a fork, or a supply-chain pull request — can read many values out of the victim's process environment and have them delivered to an attacker-controlled host. No pre-existing access to the victim's store, global config, lockfile, `node_modules`, or environment is required. The secret is exfiltrated during config loading, before any lifecycle script runs. This turns "I can author a project manifest" into "I read the victim's environment secrets." ## Affected versions Introduced in pnpm 10.7.0, which added environment-variab