Task: Create an alert on SIGNL4

n8n workflow JSON:
{"nodes":[{"name":"On clicking 'execute'","type":"n8n-nodes-base.manualTrigger","position":[250,300],"parameters":{},"typeVersion":1},{"name":"SIGNL4","type":"n8n-nodes-base.signl4","position":[450,300],"parameters":{"message":"This is a test alert sent from n8n to SIGNL4","additionalFields":{"title":"Sample Title"}},"credentials":{"signl4Api":"Signl4 Team Secret"},"typeVersion":1}],"connections":{"On clicking 'execute'":{"main":[[{"node":"SIGNL4","type":"main","index":0}]]}}}