fix(docker): use restart: on-failure to prevent restart after first-run setup

unless-stopped restarts the container regardless of exit code, causing
an infinite loop when entrypoint exits 0 after the initial onboard.
on-failure only restarts on non-zero exit (i.e. crashes), so the
container stays stopped after setup until the user restarts it manually.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker/docker-compose.yml

@@ -24,7 +24,7 @@ services:
   picoclaw-gateway:
     image: docker.io/sipeed/picoclaw:latest
     container_name: picoclaw-gateway
-    restart: unless-stopped
+    restart: on-failure
     profiles:
       - gateway
     # Uncomment to access host network; leave commented unless needed.