Fix setup failure when BMS not immediately reachable

Don't connect eagerly in async_setup — let the first coordinator poll
handle it. If the BMS is out of range at startup, UpdateFailed becomes
ConfigEntryNotReady and HA retries automatically instead of crashing.

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

custom_components/xiaoxiang_bms/coordinator.py

@@ -50,8 +50,7 @@ class BmsCoordinator(DataUpdateCoordinator[dict]):
         return device
 
     async def async_setup(self) -> None:
-        """Connect to the BMS. Called once during config entry setup."""
+        """No-op — connection is established lazily on the first poll."""
-        await self._handler.connect(self._get_ble_device())
 
     async def async_teardown(self) -> None:
         """Disconnect cleanly. Called on entry unload."""