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/const.py

@@ -0,0 +1,36 @@
+"""Constants for the Lithionics Li3 BMS integration."""
+
+DOMAIN = "li3_battery"
+
+# (key, name, unit, device_class, display_precision) -- precision None means a
+# non-numeric value (hex code, version string, serial number): published as-is,
+# no rounding, no state_class. Mirrors van-li3-battery's SENSORS list.
+SENSORS = [
+    ("voltage", "Pack Voltage", "V", "voltage", 2),
+    ("cell1_voltage", "Cell 1 Voltage", "V", "voltage", 2),
+    ("cell2_voltage", "Cell 2 Voltage", "V", "voltage", 2),
+    ("cell3_voltage", "Cell 3 Voltage", "V", "voltage", 2),
+    ("cell4_voltage", "Cell 4 Voltage", "V", "voltage", 2),
+    ("current", "Current", "A", "current", 2),
+    ("soc", "State of Charge", "%", "battery", 0),
+    ("bms_temperature", "BMS Temperature", "°F", "temperature", 1),
+    ("battery_temperature", "Battery Temperature", "°F", "temperature", 1),
+    ("remaining_capacity", "Remaining Capacity", "Ah", None, 0),
+    ("remaining_time", "Remaining Time", "min", "duration", 0),
+    ("can_charger_voltage", "CAN Charger Voltage", "V", "voltage", 1),
+    ("can_charger_current", "CAN Charger Current", "A", "current", 1),
+    ("can_charger_status", "CAN Charger Status", None, None, None),
+    ("can_status", "CAN Status", None, None, None),
+]
+
+# From the one-time "$info" response -- published as diagnostic entities.
+INFO_SENSORS = [
+    ("total_consumed", "Lifetime Consumed", "Ah", None, 0),
+    ("last_fault_code", "Last Fault Code", None, None, None),
+    ("highest_recorded_temp", "Highest Recorded Temperature", "°F", "temperature", 0),
+    ("lowest_recorded_temp", "Lowest Recorded Temperature", "°F", "temperature", 0),
+    ("firmware_version", "Firmware Version", None, None, None),
+    ("aging_factor_temp", "Aging Factor (Temp)", None, None, 0),
+    ("aging_factor_soc", "Aging Factor (SOC)", None, None, 0),
+    ("serial_number", "Serial Number", None, None, None),
+]