Logging domain

This domain centralizes how Arthexis selects log destinations and routes output from Django, Celery, and supporting scripts.

Log directory selection

• select_log_dir chooses the first writable candidate from ARTHEXIS_LOG_DIR, the repository logs/ folder, user state directories, or system fallbacks (including /var/log/arthexis when running as root). It also exports ARTHEXIS_LOG_DIR for child processes so Python and shell tooling share the same location.
• Django loads LOG_DIR via build_logging_settings, which calls select_log_dir and exposes the resolved path alongside the full LOGGING dict used by the app and Celery workers.