Full protocol coverage: binary sensors, energy, hardware version

Sensors added:
- energy_stored (kWh = V × Ah / 1000) for energy dashboard

Binary sensors added (all from existing 0x03 frame, no extra BLE requests):
- Charge MOSFET / Discharge MOSFET (MOS gate status)
- Cell Balancing (any balance bit active)
- 13× protection flags: cell/pack over/under-voltage, charge/discharge
  over/under-temperature, charge/discharge over-current, short circuit,
  frontend IC error, software lock

Other:
- Hardware version string fetched once via CMD 0x05, shown in device card
- DeviceInfo centralised on coordinator (sensor + binary_sensor share it)
- CONF_ADDRESS removed from sensor.py (coordinator holds address)

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

custom_components/xiaoxiang_bms/__init__.py

@@ -7,7 +7,7 @@ from homeassistant.core import HomeAssistant
 from .const import CONF_ADDRESS, CONF_POLL_INTERVAL, DEFAULT_POLL_INTERVAL, DOMAIN
 from .coordinator import BmsCoordinator
 
-PLATFORMS = ["sensor"]
+PLATFORMS = ["sensor", "binary_sensor"]
 
 
 async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool: