fix(rivetkit): retry connect after guard actor_ready_timeout

[eersnington]

On a runner drain, the gateway can reject a reconnect with guard.actor_ready_timeout while the actor finishes its work on the draining runner. The client did not classify this code as retryable, so the connection left its reconnect loop and stayed idle.

• Add actor_ready_timeout to isRetryableGuardGatewayHttpError in rivetkit-typescript/packages/rivetkit/src/client/lifecycle-errors.ts. This matches the engine retry list in engine/packages/guard-core/src/utils.rs.
• Connections keep reconnecting with backoff. Action calls use the existing bounded lifecycle retry.

 function isRetryableGuardGatewayHttpError(code: string): boolean {
 	return (
 		code === "service_unavailable" ||
+		code === "actor_ready_timeout" ||
 		code === "actor_wake_retries_exceeded" ||

---

This is part 1 of 6 in a stack:

•  6  fix(rivetkit-core): close attached connections at the sleep grace deadline #5871
•  5  fix(rivetkit): run onSleep after in-flight work and refuse dispatch once it starts #5860
•  4  fix(rivetkit): refuse actions after onSleep with actor.restarting #5876
•  3  fix(rivetkit-core): close drained connections with ws.going_away #5867
•  2  fix(pegboard-gateway): send the client close without waiting on the envoy #5874
•  1  fix(rivetkit): retry connect after guard actor_ready_timeout #5866 👈

[railway-app]

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[claude]

Review: PR #5866

LGTM. The change adds actor_ready_timeout to isRetryableGuardGatewayHttpError, and the matching case goes into the existing test.each table.

• Consistency: engine/packages/guard-core/src/utils.rs:484 already lists actor_ready_timeout as retryable, so the client and engine now agree. The code also maps to 503, which fits a transient condition.
• Risk: low. Action calls stay bounded by the existing lifecycle retry, and connections use the existing backoff.
• Tests: the new table entry covers the classification. I did not run the suite.

No blocking issues.