## Summary

Improves output formatting for the commitment snapshot removal command:

- **Path once**: prints snapshot directory path once at top, then
filenames only
- **Unwindable status**: replaces `found state key with kvi` →
`Unwindable` and `found state key using bt` → `Not Unwindable (*)`
- **Newline before removal list** for readability
- **File sizes**: shows per-file size and total using `common.ByteCount`

## Before
```
found state key with kvi /path/to/snapshots/domain/v2.0-commitment.112-128.kv
found state key with kvi /path/to/snapshots/domain/v2.0-commitment.16-32.kv
REMOVE /path/to/snapshots/domain/v2.0-commitment.0-16.kv
...
```

## After
```
Snapshot dir: /path/to/snapshots/domain/
  v2.0-commitment.112-128.kv  Unwindable
  v2.0-commitment.16-32.kv    Unwindable

  REMOVE v2.0-commitment.0-16.kv     (1.2 GiB)
  REMOVE v2.0-commitment.112-128.kv  (1.1 GiB)
  Total: 9.4 GiB
```

Co-authored-by: shuo <shuo@erigon.dev>

Co-authored-by: shuo <shuo@erigon.dev>

…ick #20525) (#21117)

Cherry-pick of #20525 to release/3.4.

Stacked on #21116 (cherry-pick of #20202). Merge order: 1/3 first, then
this. Change base to `release/3.4` after 1/3 lands.

…pick #20202) (#21116)