feat: implement RAG-based chatbot service with daily usage rate limiting and background index worker

pkg/constants/stream.go

@@ -3,6 +3,8 @@ package constants
 const (
 	StreamEmailName   = "stream:email_tasks"
 	StreamStorageName = "stream:storage_tasks"
+	StreamRagName     = "stream:rag_tasks"
 	GroupEmailName    = "email_workers_group"
 	GroupStorageName  = "storage_workers_group"
+	GroupRagName      = "rag_workers_group"
 )