feat: add more info about heal items and data

[majinghe]

Background

When using rc admin heal status xxx to check the heal status, althrough Heal Status shows In progress, but all Items and Data show zero, which lead to use can't make sure wheter heal really works.

rc admin heal status rustfs-new
Heal Status: In Progress

  Items:         0 scanned, 0 healed, 0 failed
  Data:          0 B scanned, 0 B healed
  Started:       2026-06-15T10:11:18.203703691Z

Expected behavior

Once Heal started, Healed items and data should be displayed.