fix(portal-self-service): health-check nginx over IPv4 (127.0.0.1) (refs #68)

nginx listens on IPv4 only (listen 80), but 'localhost' inside the container resolves
to ::1 first, so the wget healthcheck got connection-refused and self-service never
went healthy — timing out the CI stack bring-up. Probe 127.0.0.1 instead.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

infra/docker-compose.yml

@@ -445,7 +445,8 @@ services:
     ports:
       - "8140:80"
     healthcheck:
-      test: ["CMD-SHELL", "wget -q -O /dev/null http://localhost/ || exit 1"]
+      # 127.0.0.1, not localhost: nginx listens on IPv4 only, but localhost resolves to ::1 first.
+      test: ["CMD-SHELL", "wget -q -O /dev/null http://127.0.0.1/ || exit 1"]
       interval: 5s
       timeout: 3s
       retries: 5