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/config_flow.py

@@ -0,0 +1,84 @@
+"""Config flow for the Lithionics Li3 BMS integration."""
+from __future__ import annotations
+
+from typing import Any
+
+import voluptuous as vol
+
+from homeassistant.components.bluetooth import (
+    BluetoothServiceInfoBleak,
+    async_discovered_service_info,
+)
+from homeassistant.config_entries import ConfigFlow
+from homeassistant.data_entry_flow import FlowResult
+
+from .const import DOMAIN
+
+
+class Li3ConfigFlow(ConfigFlow, domain=DOMAIN):
+    """Handle a config flow for a Lithionics Li3 BMS."""
+
+    VERSION = 1
+
+    def __init__(self) -> None:
+        self._discovery_info: BluetoothServiceInfoBleak | None = None
+        self._discovered: dict[str, str] = {}
+
+    async def async_step_bluetooth(
+        self, discovery_info: BluetoothServiceInfoBleak
+    ) -> FlowResult:
+        """Handle a discovered Li3 advertisement (from any Bluetooth source)."""
+        await self.async_set_unique_id(discovery_info.address)
+        self._abort_if_unique_id_configured()
+        self._discovery_info = discovery_info
+        self.context["title_placeholders"] = {"name": discovery_info.name}
+        return await self.async_step_bluetooth_confirm()
+
+    async def async_step_bluetooth_confirm(
+        self, user_input: dict[str, Any] | None = None
+    ) -> FlowResult:
+        assert self._discovery_info is not None
+        if user_input is not None:
+            return self.async_create_entry(
+                title=self._discovery_info.name,
+                data={
+                    "address": self._discovery_info.address,
+                    "name": self._discovery_info.name,
+                },
+            )
+        return self.async_show_form(
+            step_id="bluetooth_confirm",
+            description_placeholders={"name": self._discovery_info.name},
+        )
+
+    async def async_step_user(
+        self, user_input: dict[str, Any] | None = None
+    ) -> FlowResult:
+        """Manual entry, plus a dropdown of any Li3 already seen advertising."""
+        errors: dict[str, str] = {}
+        if user_input is not None:
+            address = user_input["address"]
+            await self.async_set_unique_id(address, raise_on_progress=False)
+            self._abort_if_unique_id_configured()
+            name = self._discovered.get(address, "Li3 Battery")
+            return self.async_create_entry(title=name, data={"address": address, "name": name})
+
+        current_addresses = self._async_current_ids()
+        for info in async_discovered_service_info(self.hass, connectable=True):
+            if info.address in current_addresses:
+                continue
+            if info.name and info.name.startswith("Li3-"):
+                self._discovered[info.address] = info.name
+
+        if not self._discovered:
+            return self.async_show_form(
+                step_id="user",
+                data_schema=vol.Schema({vol.Required("address"): str}),
+                errors=errors,
+            )
+
+        return self.async_show_form(
+            step_id="user",
+            data_schema=vol.Schema({vol.Required("address"): vol.In(self._discovered)}),
+            errors=errors,
+        )