Initial commit: Xiaoxiang Smart BMS Home Assistant integration

- BLE GATT communication via bleak (UART-over-GATT, service 0xff00)
- Parses 0x03 (general info) and 0x04 (cell voltages) frames
- Protocol verified against official RS485/UART spec V4
- DataUpdateCoordinator with 5s poll interval (configurable 2-60s)
- Auto-reconnect on BLE disconnect
- Config flow: BT auto-discovery + manual MAC entry + options flow
- Sensors: voltage, current, power, SoC, capacity, cycles, temps, cells, cell delta
- HACS-ready (hacs.json, manifest.json)

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

custom_components/xiaoxiang_bms/__init__.py

@@ -0,0 +1,42 @@
+"""Xiaoxiang Smart BMS — Home Assistant integration."""
+from __future__ import annotations
+
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.core import HomeAssistant
+
+from .const import CONF_ADDRESS, CONF_POLL_INTERVAL, DEFAULT_POLL_INTERVAL, DOMAIN
+from .coordinator import BmsCoordinator
+
+PLATFORMS = ["sensor"]
+
+
+async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+    """Set up the BMS integration from a config entry."""
+    address = entry.data[CONF_ADDRESS]
+    poll_interval = entry.options.get(CONF_POLL_INTERVAL, DEFAULT_POLL_INTERVAL)
+
+    coordinator = BmsCoordinator(hass, address, poll_interval)
+    await coordinator.async_setup()
+    await coordinator.async_config_entry_first_refresh()
+
+    hass.data.setdefault(DOMAIN, {})[entry.entry_id] = coordinator
+    await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)
+
+    # Reload the entry when options (e.g. poll interval) change
+    entry.async_on_unload(entry.add_update_listener(_async_update_listener))
+
+    return True
+
+
+async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+    """Unload the BMS integration."""
+    unload_ok = await hass.config_entries.async_unload_platforms(entry, PLATFORMS)
+    if unload_ok:
+        coordinator: BmsCoordinator = hass.data[DOMAIN].pop(entry.entry_id)
+        await coordinator.async_teardown()
+    return unload_ok
+
+
+async def _async_update_listener(hass: HomeAssistant, entry: ConfigEntry) -> None:
+    """Reload the entry when options are changed."""
+    await hass.config_entries.async_reload(entry.entry_id)