perf(dev): Eliminate IPC handshake latency on startup
Pass server options via NEXT_PRIVATE_WORKER_OPTIONS environment variable
instead of using IPC message roundtrip. This eliminates the latency of:
1. Child sending nextWorkerReady
2. Parent receiving and sending nextWorkerOptions
3. Child receiving options
Now the child process reads options immediately from env and starts
the server without waiting for IPC messages.
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
