#1: fix webmail healthcheck - Next standalone binds IPv4-only, wget resolved localhost to ::1

Verified live via WSL Docker (docker compose up --wait): every other F0
service came up healthy, but web stayed unhealthy. Root cause was two
compounding issues, both invisible to static review:

1. Docker auto-sets HOSTNAME to the container ID; Next's standalone
   server.js honors that env var and binds only to it instead of all
   interfaces. Fixed by explicitly setting ENV HOSTNAME=0.0.0.0 in the
   Dockerfile, after Docker's automatic assignment.
2. Even bound to 0.0.0.0 (IPv4), the healthcheck's `wget http://localhost`
   resolved localhost to ::1 (IPv6) first inside the container, where
   nothing was listening. Fixed by pointing the healthcheck at
   127.0.0.1 explicitly instead of localhost.

Full stack (db, redis, migrate, auth, storage, protocols, web) now
reaches healthy end-to-end under docker compose up --wait.

docker-compose.yaml

@@ -118,7 +118,7 @@ services:
       auth: { condition: service_healthy }
       storage: { condition: service_healthy }
     healthcheck:
-      test: ["CMD-SHELL", "wget -qO- http://localhost:3000/health || exit 1"]
+      test: ["CMD-SHELL", "wget -qO- http://127.0.0.1:3000/health || exit 1"]
       interval: 10s
       timeout: 5s
       retries: 5

services/webmail/Dockerfile

@@ -11,4 +11,8 @@ COPY --from=build /app/.next/standalone ./
 COPY --from=build /app/.next/static ./.next/static
 COPY --from=build /app/public ./public
 EXPOSE 3000
+# Docker sets HOSTNAME to the container ID by default; Next's standalone
+# server.js honors that env var and binds only to it, refusing localhost
+# (and thus the healthcheck). Force it to listen on every interface.
+ENV HOSTNAME=0.0.0.0
 CMD ["node", "server.js"]