Add an opt-in pnpm agent server that resolves dependencies server-side
and streams only the files missing from the client's store.
Server (@pnpm/agent.server):
- Multi-process HTTP server (Node.js cluster, 9 workers)
- SQLite-backed metadata cache — resolution in ~1s vs ~3.4s with .jsonl
- Streaming NDJSON /v1/install — file digests emitted as packages resolve
- Gzip-compressed streaming /v1/files — no buffering on server or worker
- Binary protocol with server-provided digests (no client rehashing)
Client (@pnpm/agent.client):
- Streaming NDJSON parser dispatches worker batches during resolution
- Worker-thread streaming HTTP + gzip decompress + CAFS writes
- Pre-packed msgpack store index entries written directly to SQLite
- Pipelined headless install via wrapped store controller
Config: `agent: "http://host:port"` in pnpm-workspace.yaml
