feat: activate BunkerM MQTT broker + fix Telegraf

- BunkerM: recreated with port 1883 (external) -> 1900 (internal)
- BunkerM: disabled dynsec plugin, using password_file auth (bunker/bunker)
- Simulator: ENABLE_BUNKER=1, BUNKERM_PORT=1900
- Telegraf: reactivated BunkerM consumer on port 1900
- Telegraf: recreated container (3 MQTT consumers connected)
- Grafana: dashboard v4 with corrected Flux queries
- Grafana: datasource fixed (bucket=smartcity, token=my-super-token)

Verified:
- Simulator publishes to EMQX ✅, Mosquitto ✅, BunkerM ✅
- Telegraf receives from all 3 brokers ✅
- InfluxDB has data from all brokers ✅
- Grafana dashboard displays data ✅

docker-compose.bunkerm.yml

@@ -0,0 +1,35 @@
+# BunkerM MQTT Broker - Smart City Digital Twin
+version: '3.8'
+
+networks:
+  smartcity-shared:
+    external: true
+  traefik-public:
+    external: true
+
+volumes:
+  bunkerm_mosquitto_data:
+    external: true
+
+services:
+  bunkerm:
+    image: bunkeriot/bunkerm:latest
+    container_name: bunkerm-bunkerm-1
+    restart: unless-stopped
+    networks:
+      - smartcity-shared
+      - traefik-public
+    ports:
+      - "1883:1900"
+      - "2000:2000"
+    environment:
+      - MQTT_PORT=1900
+      - CONFIG_API_PORT=2000
+    volumes:
+      - bunkerm_mosquitto_data:/var/lib/mosquitto
+    healthcheck:
+      test: ["CMD-SHELL", "bash -c 'echo > /dev/tcp/localhost/1900' || exit 1"]
+      interval: 30s
+      timeout: 10s
+      retries: 5
+      start_period: 60s