node-download-mirrors was never registered in pnpmTypes. Both the pnpm_config_* environment pass and the global config file allowlist work off that schema, so the setting was invisible to both.
nodeDownloadMirrors could only be read from a pnpm-workspace.yaml, which is per-project config, so a Node.js download mirror could not easily be configured once for a machine.
This commit registers the key, updates the env parser to accept a JSON object, and adds it to the global config file allowlist.
The Rust stack already read this setting from both the environment and the global config file. To keep parity, this commit gives its config_types.rs mirror of
pnpmConfigFileKeys the same entry, so the Rust `pnpm config set -g` honours the key.
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Co-authored-by: Zoltan Kochan <z@kochan.io>
