fix: make docker entrypoint restart-safe

docker compose restart reuses the container, so the overlay fs keeps the
user created on first boot; a second useradd fails with exit code 9 and
set -e kills the container on every restart (crash loop, bot never comes
back). Create the user only if missing, align UID otherwise, and never
let chown failure on bind-mounted volumes kill the container.

Also comment out nginx-proxy's empty environment block in the compose
example: an empty mapping fails validation on newer compose versions
(must be a mapping).

docker-compose.yml.example

@@ -5,8 +5,8 @@ services:
     ports:
       - '80:80'
       - '443:443'
-    environment:
-      # Bare-IP access only.
+    # Bare-IP access only. Uncomment to enable.
+    # environment:
     #   DEFAULT_HOST: 'bot.example.com'
     volumes:
       - /var/run/docker.sock:/tmp/docker.sock:ro

docker-entrypoint.sh

@@ -5,9 +5,21 @@ if [ "$(id -u)" -eq '0' ]
 then
    USER_ID=${LOCAL_USER_ID:-9001}
 
-   useradd --shell /bin/bash -u ${USER_ID} -o -c "" -m user > /dev/null 2>&1
-   usermod -a -G root user > /dev/null 2>&1
-   chown -R `id -u user`:`id -u user` /app > /dev/null 2>&1
+   # `docker compose restart` / `docker restart` reuse the same container, so
+   # the overlay fs keeps the user created on first boot. A second `useradd`
+   # then fails with exit code 9, which would trip `set -e` and kill the
+   # container on every restart. Create only if missing; align the UID
+   # otherwise so LOCAL_USER_ID changes still apply.
+   if ! id user > /dev/null 2>&1
+   then
+      useradd --shell /bin/bash -u ${USER_ID} -o -c "" -m user > /dev/null 2>&1 || true
+   else
+      usermod -u ${USER_ID} -o user > /dev/null 2>&1 || true
+   fi
+   usermod -a -G root user > /dev/null 2>&1 || true
+   # Bind-mounted volumes may not support chown; a failure here must not kill
+   # the container either.
+   chown -R `id -u user`:`id -u user` /app > /dev/null 2>&1 || true
 
    export HOME=/home/user
    # setpriv (util-linux, present in bookworm-slim) replaces gosu: drop to the