Debug mode logs SSH password in plaintext

[nitrobass24]

Description

When debug mode is enabled, the startup config dump logs Lftp.remote_password in plaintext to the container logs:

DEBUG - seedsync - Config:
  ...
  Lftp.remote_password: <actual password visible here>
  ...

This is a security concern because:

• Container logs are often collected by logging aggregators (Loki, CloudWatch, etc.)
• docker logs seedsync exposes the password to anyone with Docker access
• Log files may persist on disk and be included in bug reports

Expected behavior

The password should be masked in log output, e.g.:

Lftp.remote_password: ********

Steps to reproduce

1. Enable debug mode in Settings
2. Restart the container
3. Run docker logs seedsync
4. Password is visible in the config dump

Suggested fix

Mask sensitive fields (remote_password) in the config debug output.