Make internal and host ports configurable via env vars

docker-compose.yml

@@ -1,15 +1,12 @@
 services:
   booth:
-    # Option A: use a pre-built image (push this from CI or build locally and tag)
-    # image: registry.gitlab.hallsworth.ca/yrtria/theme-song-booth:latest
-    # Option B: build directly from the GitLab repo in Portainer
     build:
       context: https://gitlab.hallsworth.ca/yrtria/theme-song-booth.git#main
     container_name: theme-song-booth
     restart: unless-stopped
     env_file: .env
     ports:
-      - "127.0.0.1:8000:8000"
+      - "${HOST_PORT:-127.0.0.1:8000}:${INTERNAL_PORT:-8000}"
     volumes:
       - booth-data:/app/data
       - booth-uploads:/app/uploads