feat: replace iot adapter with mqtt command pipeline

backend/iot-server/etc/platform_iot_server_dev.yaml

@@ -0,0 +1,23 @@
+Service: platform-iot-server
+MQTT:
+  Broker: tcp://127.0.0.1:1883
+  ClientID: heqi-iot-server-dev
+  Username: heqi-dev
+  Password: change-me
+  UpTopic: devices/+/up
+  DownTopic: devices/{deviceId}/down
+  AckTopic: devices/+/ack
+  QoS: 1
+  TLS: false
+  CAFile: ""
+  CertificateFile: ""
+  PrivateKeyFile: ""
+HTTP:
+  Address: 127.0.0.1:12428
+  InternalToken: change-me-iot-internal-token
+  CallbackURL: http://127.0.0.1:12429/internal/v1/device-messages
+Protocol:
+  # 仅为本地开发占位。生产通过 HEQI_IOT_KEY_1/2/3 或密钥注入覆盖。
+  Key1: "00000000000000000000000000000000"
+  Key2: "11111111111111111111111111111111"
+  Key3: "22222222222222222222222222222222"