v0.2.25

Direct and group consumers now negotiate Fetch v12/v11 without requiring client_rack and reuse broker-scoped fetch sessions across polls. Fetch v4 remains the fallback when the broker advertises neither session-capable version. Verified with 311 workspace tests, all-feature lint/docs, the complete 17-job Live Kafka Smoke matrix, crates.io publishing, docs.rs, and a fresh external TLS compile.