ha: add li3_battery HA integration, replacing van-li3-battery

The li3 BMS has a persistently marginal BLE link from any single fixed
vantage point on this Pi (onboard adapter, a USB dongle that turned out to
be BR/EDR-only, and the Athom ESPHome BT proxy even after moving it closer).
Move capture into HA proper so bluetooth.async_ble_device_from_address can
pick whichever known source currently has the device, instead of hardcoding
one. Protocol parsing ported verbatim from li3/van-li3-battery.

van-li3-battery is disabled on the Pi; its MQTT discovery entities were
cleared.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

ha/custom_components/li3_battery/__init__.py

@@ -0,0 +1,27 @@
+"""The Lithionics Li3 BMS integration."""
+from __future__ import annotations
+
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.const import Platform
+from homeassistant.core import HomeAssistant
+
+from .const import DOMAIN
+from .coordinator import Li3Coordinator
+
+PLATFORMS: list[Platform] = [Platform.SENSOR]
+
+
+async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+    coordinator = Li3Coordinator(hass, entry.data["address"])
+    await coordinator.async_start()
+    hass.data.setdefault(DOMAIN, {})[entry.entry_id] = coordinator
+    await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)
+    return True
+
+
+async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+    unload_ok = await hass.config_entries.async_unload_platforms(entry, PLATFORMS)
+    if unload_ok:
+        coordinator: Li3Coordinator = hass.data[DOMAIN].pop(entry.entry_id)
+        await coordinator.async_stop()
+    return unload_ok