Concord backup management tasks.
Usage
# Create a backup
mix concord.backup create
# Create backup in specific directory
mix concord.backup create --path /mnt/backups
# List available backups
mix concord.backup list
# Restore from backup
mix concord.backup restore <backup_file>
# Verify backup integrity
mix concord.backup verify <backup_file>
# Clean up old backups
mix concord.backup cleanup --keep-count 5