WAL writes during checkpoint are redundant since the binary snapshot
captures all in-memory data. Pausing eliminates channel saturation
(1.4M+ dropped messages) caused by disk I/O contention between
checkpoint writes and WAL staging. Also removes direct WAL file
deletion in checkpoint workers that raced with the staging goroutine.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Entire-Checkpoint: 34d698f40bac