[feature]: clean up `log.Info` / `log.Debug`

## Audit and clean up `log.Info` / `log.Debug` usage across the codebase

### Summary

User-facing confirmation messages (success/status output) should go through `fmt.Printf`, not `log.Infof`. Log statements are for structured logging and debug output, mixing them with CLI output makes the output behavior unpredictable (depends on log level, log format, log destination).

This is a tracking issue to ensure all `log.Info` and `log.Debug` statements are reviewed and classified.

### Rules

| Statement | When to use |
|-----------|-------------|
| `fmt.Printf` / `fmt.Println` | User-facing output: success confirmations, status updates |
| `log.Debugf` | Internal steps useful for debugging, not shown by default |
| `log.Infof` | Should generally not be used for CLI output |
| `log.Errorf` | Shall not be used anymore and will be retired by #635 |

### Tasks

- [ ] Audit all remaining `log.Infof` calls, classify as user-facing or debug, #883
- [ ] Audit all `log.Debugf` calls, verify they are actually debug-relevant