feat: replace MQTT bridge with localthings HA custom component
Convert from MQTT bridge architecture to a proper Home Assistant
integration (custom_components/localthings/):
- Config flow: IP-only entry, probes ports [49154,49155], cert/key
reused from first device on subsequent adds
- Coordinator: DataUpdateCoordinator wrapping blocking DTLS session
via async_add_executor_job; discovery on first poll; dynamic 5s/30s
interval based on active_when
- Entity platforms: sensor, binary_sensor, switch, number, select
- Library cleanup: delete bridge.py, main.py, config.py, logger.py,
keepalive.py, poll_scheduler.py, sensors.py, state_cache.py
- adapter.py stripped to flatten(), is_active(), _key()
- _parse_device0_batch moved to samsung_appliance/batch.py