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/const.py

@@ -17,6 +17,7 @@ TX_CHAR_UUID      = "0000ff02-0000-1000-8000-00805f9b34fb"  # HA → BMS (write)
 # Request frames: [0xDD, 0xA5, CMD, 0x00, CHK_HI, CHK_LO, 0x77]
 CMD_GENERAL = bytes([0xDD, 0xA5, 0x03, 0x00, 0xFF, 0xFD, 0x77])  # pack info
 CMD_CELL    = bytes([0xDD, 0xA5, 0x04, 0x00, 0xFF, 0xFC, 0x77])  # cell voltages
+CMD_VERSION = bytes([0xDD, 0xA5, 0x05, 0x00, 0xFF, 0xFB, 0x77])  # hardware version string
 
 # Frame markers
 FRAME_START = 0xDD
@@ -25,3 +26,4 @@ FRAME_END   = 0x77
 # Response command IDs (byte 1 of frame)
 CMD_ID_GENERAL = 0x03
 CMD_ID_CELL    = 0x04
+CMD_ID_VERSION = 0x05