fix(config): 修改设备ID默认值为default - 匹配云端配置

- device_id: edge → default
- 修复云端推送空配置的问题
- 云端摄像头配置的device_id都是default，需要匹配

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

config/settings.py

@@ -71,7 +71,7 @@ class MQTTConfig:
     broker_host: str = "localhost"
     broker_port: int = 1883
     client_id: str = "edge_inference_service"
-    device_id: str = "edge"
+    device_id: str = "default"
     username: Optional[str] = None
     password: Optional[str] = None
     keepalive: int = 60
@@ -242,7 +242,7 @@ class Settings:
             broker_host=os.getenv("MQTT_BROKER_HOST", "localhost"),
             broker_port=int(os.getenv("MQTT_BROKER_PORT", "1883")),
             client_id=os.getenv("MQTT_CLIENT_ID", "edge_inference_service"),
-            device_id=os.getenv("EDGE_DEVICE_ID", "edge"),
+            device_id=os.getenv("EDGE_DEVICE_ID", "default"),
             username=os.getenv("MQTT_USERNAME"),
             password=os.getenv("MQTT_PASSWORD"),
         )