Docker Compose + CloudNet v4 deployment config for alpha server

Description

The alpha server must be deployable reliably. We need a Docker Compose setup for the full stack (Minestom server + MariaDB) for local testing, and a CloudNet v4 service template that can host the game server for remote alpha testers.

Acceptance Criteria

• docker/alpha/compose.yml starts Minestom game server + MariaDB with correct networking
• Game server JAR (server/build/libs/*.jar) is packaged into a Docker image (Dockerfile in server/)
• Environment variables for DB config are passed through Docker Compose env file
• CloudNet v4 service template YAML is defined and committed to deploy/cloudnet/
• Template specifies: server type, memory allocation (512MB min, 1GB max), JAR path, env vars
• README or ADR documents the deployment procedure for alpha
• CI job (ci-deploy.yml) builds the shadow JAR and Docker image on push to main

Technical Details

• CloudNet v4 uses task/template system — see CloudNet docs
• Minestom server listens on 0.0.0.0:25565 by default
• Shadow JAR built via ./gradlew :server:shadowJar

Dependencies

• "Wire database service" must be done first (so the server actually starts with DB)

Estimate

M

Start with the dependency on “Wire database service,” then inspect the requested paths: docker/alpha/compose.yml, server/Dockerfile, deploy/cloudnet/, README or ADR, and ci-deploy.yml. Read the CloudNet v4 task/template documentation and run ./gradlew :server:shadowJar. Done means the Compose stack, CloudNet template, deployment documentation, and main-branch CI job satisfy every acceptance criterion.