Aggiunta configurazione tramite variabili d'ambiente e fix Docker Hub secrets

- Aggiunto supporto ENV variables nel Dockerfile:
  * INVERTER_DEVICE, MQTT_SERVER, MQTT_PORT, MQTT_TOPIC
  * MQTT_DEVICENAME, MQTT_USERNAME, MQTT_PASSWORD
  * FORCE_DISCOVERY, SKIP_DISCOVERY
- Implementata funzione update_mqtt_config() in entrypoint.sh
  * Aggiorna automaticamente mqtt.json da ENV variables all'avvio
  * Backup automatico configurazione originale
- Fix workflow Docker build:
  * Login Docker Hub solo se secrets configurati
  * Push solo se secrets disponibili (evita errori CI/CD)
  * Build funziona anche senza secrets (utile per test locali)
- Aggiornato docker-compose.yml con esempio ENV variables
- Creata documentazione completa DOCKER_SETUP.md:
  * Guida configurazione variabili d'ambiente
  * Esempi docker-compose e docker run
  * Guida configurazione secrets Gitea
  * Troubleshooting e health check

Ora è possibile configurare completamente il container senza modificare file

sources/inverter-mqtt/entrypoint.sh

@@ -14,13 +14,50 @@ TEMP_CONF="/tmp/inverter_discovered.conf"
 INVERTER_DEVICE="${INVERTER_DEVICE:-/dev/ttyUSB0}"
 FORCE_DISCOVERY="${FORCE_DISCOVERY:-false}"
 SKIP_DISCOVERY="${SKIP_DISCOVERY:-false}"
+MQTT_SERVER="${MQTT_SERVER:-192.168.1.37}"
+MQTT_PORT="${MQTT_PORT:-1883}"
+MQTT_TOPIC="${MQTT_TOPIC:-homeassistant}"
+MQTT_DEVICENAME="${MQTT_DEVICENAME:-voltronic}"
+MQTT_USERNAME="${MQTT_USERNAME:-}"
+MQTT_PASSWORD="${MQTT_PASSWORD:-}"
 
 echo "Configuration:"
 echo "  Device: $INVERTER_DEVICE"
 echo "  Force Discovery: $FORCE_DISCOVERY"
 echo "  Skip Discovery: $SKIP_DISCOVERY"
+echo "  MQTT Server: $MQTT_SERVER:$MQTT_PORT"
+echo "  MQTT Topic: $MQTT_TOPIC"
+echo "  MQTT Device: $MQTT_DEVICENAME"
 echo ""
 
+# Function to update MQTT configuration
+update_mqtt_config() {
+    local mqtt_conf="/etc/inverter/mqtt.json"
+    echo "Updating MQTT configuration from environment variables..."
+    
+    # Backup original
+    cp $mqtt_conf ${mqtt_conf}.backup
+    
+    # Update MQTT settings using jq
+    jq --arg server "$MQTT_SERVER" \
+       --arg port "$MQTT_PORT" \
+       --arg topic "$MQTT_TOPIC" \
+       --arg devicename "$MQTT_DEVICENAME" \
+       --arg username "$MQTT_USERNAME" \
+       --arg password "$MQTT_PASSWORD" \
+       '.server = $server | .port = $port | .topic = $topic | .devicename = $devicename | .username = $username | .password = $password' \
+       $mqtt_conf > ${mqtt_conf}.tmp && mv ${mqtt_conf}.tmp $mqtt_conf
+    
+    echo "✓ MQTT configuration updated"
+    echo "  Server: $MQTT_SERVER:$MQTT_PORT"
+    echo "  Topic: $MQTT_TOPIC/sensor/$MQTT_DEVICENAME"
+    [ ! -z "$MQTT_USERNAME" ] && echo "  Auth: Enabled (username: $MQTT_USERNAME)"
+    echo ""
+}
+
+# Update MQTT config from ENV on startup
+update_mqtt_config
+
 # Function to update config file with discovered values
 update_config_with_discovery() {
     local qmod=$1