//! Embedded storage engine components.
/// On-disk format version markers.
/// Cluster node metadata (format v5 additive).
/// Append-only hot segment tails (direct-write path).
/// Write-ahead logging and recovery.
/// Per-session WAL files (peer track Phase 3).
/// Per-session fast durability segments (peer track Phase 7).
/// NVMe-friendly block store and cache.
/// Block compaction routines.
/// Retention policy and garbage collection helpers.
/// Storage-layer error types.