Fix docker-compose problems

[SenequeZ]

Multi-service / Docker Compose challenges

For challenges that need more than one container (databases, sidecars, custom
networks/volumes), drop a standard Docker Compose file next to your
challenge.yml:

data/challenges/web/my-chall/
├── challenge.yml
└── docker-compose.yml

Galvanize auto-detects the first of compose.yaml, compose.yml,
docker-compose.yaml, or docker-compose.yml in the challenge directory,
validates it, and deploys it. When a compose file is present, playbook_name
defaults to custom_compose, so a minimal challenge.yml is enough:

name: my-chall
author: YourName
category: web
type: zync

deploy_parameters:
  unique: false

This lets you develop and test the stack locally with a plain
docker compose up, then ship the file unchanged.

Exposing services (expose)

Compose challenges no longer need hand-written Traefik labels, manual network
wiring, or hand-picked host ports. Declare an expose block and Galvanize wires
the networking for you — the same automation the http/tcp playbooks provide
for single containers:

deploy_parameters:
  unique: false
  expose:
    - service: web      # HTTP via Traefik → auto domain + SSL
      port: 80
      type: http
    - service: ssh      # raw TCP → published host port
      port: 22
      type: tcp
      scheme: ssh       # optional, only affects the rendered connection URL

For each entry Galvanize will, on deploy:

• type: http — attach the service to the external Traefik network, add the
  traefik.enable + router/service labels, and route
  https://<project>.<instancer_host>/ to it (when more than one HTTP service
  is exposed, each gets a <service>-<project>.<instancer_host> subdomain).
  Requires traefik_network in instancer.extra_deployment_parameters.
• type: tcp — publish the container port. With
  instancer.randomize_published_ports enabled, the host port is randomized per
  team and persisted, so instances don't collide.

Connection info is returned automatically from the resulting Traefik route or
published port.

[28Pollux28]

I'll fix the CI in a dedicated PR