chore(env): Update example env

Author: LucienShui

example.env

@@ -16,6 +16,10 @@ OBB_MAIL_FROM="OmniBox <no-reply@example.com>"
 
 OBW_BACKEND_BASE_URL=http://backend:8000
 
+OBW_KAFKA_BROKER="kafka:9092"
+
+OBW_VECTOR_DIMENSION="1536"
+
 # >>> AI Service Configuration >>>
 OBW_VECTOR_EMBEDDING_API_KEY="sk-***"
 OBW_VECTOR_EMBEDDING_BASE_URL="https://api.openai.com/v1"
@@ -66,5 +70,3 @@ OBB_S3_BUCKET=omnibox-test
 
 OBB_KAFKA_BROKER=localhost:9092
 OBB_KAFKA_CLIENT_ID=omnibox-backend
-
-OBW_KAFKA_BROKER="kafka:9092"