When nanobot is run as a systemd service with ProtectSystem=strict,
the process cwd defaults to the read-only root filesystem (/). botpy's
default Client configuration includes a TimedRotatingFileHandler that
writes 'botpy.log' to os.getcwd(), which raises [Errno 30] Read-only
file system.
Pass ext_handlers=False when constructing the botpy Client subclass to
suppress the file handler. nanobot already routes all log output through
loguru, so botpy's file handler is redundant.
Fixes#1343
Co-Authored-By: Claude <noreply@anthropic.com>