Resumed cloud sessions can connect early, with held event delivery

What

When Claude Code resumes a session running in the cloud (a CCR session, started with --sdk-url), it can now open its remote connection while the rest of startup is still running.

• A new environment variable, CLAUDE_CODE_CCR_EARLY_REMOTE_CONNECT, turns this on. CLAUDE_CODE_CCR_EARLY_HYDRATE_PREFETCH still triggers early loading of session data. Either one, plus --sdk-url and a resume, starts startEarlyRemoteWork, which replaces startEarlyHydrateReads and returns both the data reads and a remote link. Nothing starts early when no auth headers are present.
• Both variables were added to the lists of environment variables that are passed through to child processes.
• The SSE transport (the streaming connection that carries events) has a new deferDelivery option. When set, incoming frames and close events are held and then replayed by startDelivery(), passing each held frame's worker attestation policy reading along in order. The early path uses deferDelivery: !0; the main path uses deferDelivery: !1.
• The remote IO layer accepts an earlyRemoteLink and reuses the already-connected transport and client instead of building its own, calling startDelivery() rather than connect(). This is valid only for a process that owns its remote IO.
• A new takeWorkerAttestationPolicy records the attestation policy and reports any fault, and the idle tracker is no longer set up at declaration.

Why

A resumed cloud worker can register and open its stream sooner, which should shorten a cold resume, and holding events means an early request is not lost before the session is ready. Nothing changes unless the host sets one of the environment variables.