feat: enhance Dockerfile for SQLite support and update main.go for MySQL connection; add sensor creation endpoint and improve wait-for-mqtt script

scripts/wait-for-mqtt.sh

@@ -18,5 +18,22 @@ while ! nc -z "$HOST" "$PORT"; do
   sleep 1
 done
 
-echo "Broker $HOST:$PORT is up, starting server"
+echo "Broker $HOST:$PORT is up"
+
+# Optionally wait for MySQL if DB_HOST/DB_PORT are set
+DB_HOST=${DB_HOST:-}
+DB_PORT=${DB_PORT:-}
+if [ -n "$DB_HOST" ]; then
+  if [ -z "$DB_PORT" ]; then
+    DB_PORT=3306
+  fi
+  echo "Waiting for MySQL $DB_HOST:$DB_PORT..."
+  while ! nc -z "$DB_HOST" "$DB_PORT"; do
+    echo "mysql not ready, retrying..."
+    sleep 1
+  done
+  echo "MySQL $DB_HOST:$DB_PORT is up"
+fi
+
+echo "Starting server"
 exec /usr/local/bin/server