Switch logging to Loguru

[crossjam]

Goal

Switch Soco Scribbler logging to Loguru so we get structured logging with minimal boilerplate.

Checklist

• Review the existing logging flow and identify replacement points for Loguru
• Add Loguru as a dependency and configure a shared logger initialization
• Update modules to use Loguru (including custom_print replacements)
• Provide configuration guidance for file/stdout sinks in docs
• Validate logging output across CLI commands and background monitoring