Fix service workers

deploy/runbook.md

@@ -6,6 +6,9 @@ The deployment model is:
 - CI builds and publishes a Docker image containing the built static site
 - the server updates by pulling that image and restarting the service
 
+Build-time config (examples):
+- `PUBLIC_ENABLE_SW=true|false` toggles service worker registration in the generated HTML (defaults to `true` in the Docker build).
+
 ### Prerequisites
 
 - Docker + Docker Compose plugin available on the host
@@ -81,4 +84,3 @@ The pull should fail, but the current service should still be running:
 docker compose -f deploy/docker-compose.prod.yml ps
 curl -fsS http://localhost:8080/ > /dev/null
 ```
-