Fix Node's built-in WebSocket close event through container intercept

PR #1932 proves duplex frames for Node's built-in client, full close semantics for ws@8.21.0, and a stock Codex turn. The built-in client alone misses the fixture's reciprocal close event after its own 1000 close.

Done when the built-in client receives the exact close code and reason through container intercept in sandbox-egress.e2e.test.ts.