Add HCHO / VOC air-quality sensors (T9 module)
Support the WSLink t9 air-quality module:
- t9hcho (formaldehyde, ppb),
- t9voclv (VOC level 1-5 -> ENUM state)
- t9bat (0-5 battery -> percentage).
The t9hcho/t9voclv/t9bat values are dropped when
t9cn reports the module as disconnected,
so no empty entities are created.
- const: HCHO/VOC/T9_BATTERY keys, VOCLevel enum +
VOC_LEVEL_MAP, BATTERY_NON_BINARY, CONNECTION_GATED_SENSORS,
REMAP_WSLINK_ITEMS entries
- utils: voc_level_to_text(),
battery_5step_to_pct(), connection gating
- sensors_wslink: HCHO / VOC / T9_BATTERY entity
descriptions
- translations (en, cs): hcho, voc (+ states),
t9_battery
- tests: tests/conftest.py +
tests/test_t9_air_quality.py