feat: Add per-device transport diagnostics (Cloud API / MQTT / BLE)

Every Govee device entity now exposes three transport diagnostic
attributes visible in the HA entity details UI:

- transport_cloud_api: always True (REST API is the baseline)
- transport_mqtt: True when AWS IoT MQTT push is connected
- transport_ble: True when a local Bluetooth connection is active

These show up as state attributes on every light, fan, switch, sensor,
select, and button entity — no separate diagnostic sensor needed.

Also adds a per-device "transport" block to the diagnostics download
(Settings → Devices → Govee → Download diagnostics) so troubleshooting
reports include which transports each device is using.

Changes:
- entity.py: extra_state_attributes property on GoveeEntity base class
- coordinator.py: is_ble_available(device_id) public method
- diagnostics.py: per-device transport block in diagnostic dump

Author: Tom Lasswell

custom_components/govee/coordinator.py

@@ -224,6 +224,10 @@ def mqtt_connected(self) -> bool:
         """Return True if MQTT client is connected."""
         return self._mqtt_client is not None and self._mqtt_client.connected
 
+    def is_ble_available(self, device_id: str) -> bool:
+        """Return True if a BLE transport is active for this device."""
+        return device_id in self._ble_devices
+
     @property
     def states(self) -> dict[str, GoveeDeviceState]:
         """Get current states for all devices."""

custom_components/govee/diagnostics.py

@@ -61,6 +61,11 @@ async def async_get_config_entry_diagnostics(
                 "color_temp_kelvin": state.color_temp_kelvin if state else None,
                 "source": state.source if state else None,
             },
+            "transport": {
+                "cloud_api": True,
+                "mqtt": coordinator.mqtt_connected,
+                "ble": coordinator.is_ble_available(device_id),
+            },
         }
 
     # Collect MQTT status

custom_components/govee/entity.py

@@ -4,11 +4,12 @@
 - Device info
 - Coordinator integration
 - State updates
+- Transport diagnostics (Cloud API / MQTT / BLE)
 """
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 from homeassistant.helpers.device_registry import DeviceInfo
 from homeassistant.helpers.update_coordinator import CoordinatorEntity
@@ -85,6 +86,21 @@ def device_state(self) -> GoveeDeviceState | None:
         """Get current device state from coordinator."""
         return self.coordinator.get_state(self._device_id)
 
+    @property
+    def extra_state_attributes(self) -> dict[str, Any]:
+        """Return transport protocol diagnostics for this device.
+
+        Shows which communication channels are active:
+        - cloud_api: always True (REST API is the baseline transport)
+        - mqtt: True when AWS IoT MQTT push is connected
+        - ble: True when a local Bluetooth connection is available
+        """
+        return {
+            "transport_cloud_api": True,
+            "transport_mqtt": self.coordinator.mqtt_connected,
+            "transport_ble": self.coordinator.is_ble_available(self._device_id),
+        }
+
     @staticmethod
     def _infer_area_from_name(name: str) -> str | None:
         """Infer area from device name.