Squirix Preview.6 Reworks Write-Ahead Log for Crash Safety

Squirix, an experimental distributed cache, introduces a pipelined binary write-ahead log in preview.6 to ensure crash recovery and idempotent mutations. The new design moves file I/O off request threads to a dedicated background thread, preventing acknowledged-but-unrecoverable writes. It also handles 'commit unknown' states where a mutation may have committed but the client didn't receive confirmation.