test: add comprehensive client.py tests for _parse_fire_features, lifecycle, _request, and turn_on/off

Add tests covering _parse_fire_features (all 24 fields), client
__init__/__aenter__/__aexit__ lifecycle, _request auth/error handling,
get_fires/get_fire_overview field-level verification, write_parameters,
and turn_on/turn_off with mode/temperature preservation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: deviantintegral