Requested changes:
1. Classify under the checkpoint section alongside checkpoint duration and progress state.
2. Render as a percentage (percentage only exists in metric's name so it's not directly clear it's a percentage)
3. Add a helpful tooltip

there are probably more unknowns that can be classified under checkpoint

some that claude found

  number of pages reconciled by checkpoint parallel worker threads                     2026-03-04     WT-14519
  total time (msecs) writing pages to stable storage during checkpoint reconciliation  2026-03-20     WT-16888
  number of bytes reconciled                                                           2026-04-24     WT-16793
  the percentage of checkpoint sync time spent in reconciliation across all threads   2026-05-05     WT-17334
  metadata operations applied during disaggregated checkpoint                          2026-05-17     WT-17087
  metadata operations skipped during disaggregated checkpoint because not stable       2026-05-17     WT-17087
  number of pages whose reconciliation was skipped because eviction already reconciled 2026-08-13     WT-17681