[Feature Request] Secure credential handling for multi-machine file sharing without exposing secrets in logs

**Bug Description**
this is a personal tool to connect across my machines not ssh to share files over thunderbolt and lan in aggregation, often use it to let my agents to reach to another machine without providing them with ssh or a key. earlier looked into concealing password from the logs that stay in console so that agents don't see it even when i type it to allow a sudo operation and the entire project got flagged.

**Environment Info**
- Platform: darwin
- Terminal: ghostty
- Version: 2.1.236
- Feedback ID: 107ff31d-d3cb-4981-ae45-05a2eab133f0

**Errors**
```json
[]
```

The issue names no files, tests, or entry points. First clarify the credential-handling threat model and identify where sudo input and console logging are handled; done should mean secrets are not exposed to agents or retained in logs during the described workflow.

索引モデルが issue の本文から書いたものです。