Add persistent logging for warnings and errors

[SeanClay10]

Summary

Adds persistent warning/error logging across the pipeline using Python's standard logging module. All existing CLI output is unchanged. Warnings and errors now additionally write to a rotating log file that persists between runs.

Changes

• Add src/utils/logging_config.py — configures persistent file-based logging for the project
• Entry-point scripts opt in to logging by calling setup_logging() at startup
• All warning and error sites now write to the log file in addition to printing to the terminal

Behaviour

• Log file: logs/fracfeed.log, rotating at 5 MB, 5 backups kept
• Only WARNING and above is persisted