feat(iot): Этапы 2-7 — MQTT auth, IoT API, EMQX, mqtt-bridge, E2E demo

Этап 2+4: internal/api/handler/iot_device_handler.go
  - MQTTAuth: POST /internal/mqtt/auth (без JWT, для EMQX)
  - CreateIoTDevice, ListIoTDevices, GetIoTDevice (c password), DeleteIoTDevice, UpdateIoTDevice
  - crypto/subtle.ConstantTimeCompare против timing attacks

Этап 4: internal/api/router.go
  - /v1/namespaces/{ns}/iot/devices CRUD
  - /internal/mqtt/auth (без JWT middleware)

Этап 3: deployments/k8s/emqx.yaml
  - EMQX 5.5.1, emqx.conf (HOCON) с HTTP auth backend
  - Сервис exposure: 1883 (MQTT), 8083 (WS), 18083 (Dashboard)

Этап 3: iot/cmd/mqtt-bridge/main.go
  - paho.mqtt.golang: подписка на +/telemetry/+
  - amqp091-go: publish в iot.{namespace}.telemetry
  - deployments/k8s/iot-mqtt-bridge.yaml

Этап 7: examples/IOT/ — E2E demo (main.tf, handler.py, README.md)

go.mod: добавлен github.com/eclipse/paho.mqtt.golang v1.5.1
go build ./... — ошибок нет

examples/PG_TEST/.gitignore

@@ -0,0 +1,21 @@
+# Terraform provider plugins
+.terraform/
+.terraform.lock.hcl
+
+# Terraform state
+terraform.tfstate
+terraform.tfstate.backup
+*.tfstate
+*.tfstate.backup
+
+# Sensitive data
+terraform.tfvars
+!terraform.tfvars.example
+
+# Backup files
+*.bak
+*.bak_db
+*.bak_*
+
+# Test artifacts
+test_*.log