[CHA-4943] Recover from GCP LB TLS half-close EOF

[itsmeadi]

Ticket

• https://linear.app/stream/issue/CHA-4943/ruby-sdk-pooled-tls-eof-against-gcp-load-balancers

Summary

Follow-up to #78 (idle_timeout 55→25). GCP load balancers half-close idle keep-alive TLS without close_notify. OpenSSL 3 makes Net::HTTP's dead-socket probe raise SSL_read: unexpected eof while reading instead of reconnecting, so lowering idle timeout is not enough.

Set OP_IGNORE_UNEXPECTED_EOF so the probe reports a dead socket and reconnects before GET or POST is sent. Restore max_retries=1 (Faraday had forced 0) as a GET/HEAD backstop. Classify that EOF as connection_reset, not tls_handshake_failed.

Previous PR

• fix: close pooled TLS before GCP LB idle timeout [CHA-4943] #78

Checklist

• The changed code has been covered with unit tests
• API endpoints are covered with client tests
• The internal documentation (./docs) has been updated

Notes for review

• OP_IGNORE_UNEXPECTED_EOF is process-global. Net::HTTP has no per-connection SSLContext options hook. It only relaxes unclean-shutdown detection back to OpenSSL 1.1.1 behavior.
• Custom http_client: connections skip this (caller owns TLS).
• Needs a gem release after merge; PrizePicks is still on 8.0.2.

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