codex-client

Generic transport layer that wraps HTTP requests, retries, and streaming primitives without any Codex/OpenAI awareness.

• Defines HttpTransport and a default ReqwestTransport plus thin Request/Response types.
• Provides retry utilities (RetryPolicy, RetryOn, run_with_retry, backoff) that callers plug into for unary and streaming calls.
• Supplies the sse_stream helper to turn byte streams into raw SSE data: frames with idle timeouts and surfaced stream errors.
• Consumed by higher-level crates like codex-api; it stays neutral on endpoints, headers, or API-specific error shapes.