server: project config and infrastructure setup

Add package.json (Fastify, Prisma, Redis, JWT), TypeScript config,
Dockerfile, docker-compose with Postgres and Redis services, and
.gitignore with data directory rules.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/.env.example

@@ -0,0 +1,12 @@
+NODE_ENV=development
+PORT=3000
+
+DATABASE_URL=postgresql://gameuser:gamepassword@db:5432/game
+REDIS_URL=redis://redis:6379
+
+JWT_SECRET=change_me_in_production
+JWT_EXPIRES_IN=7d
+
+POSTGRES_DB=game
+POSTGRES_USER=gameuser
+POSTGRES_PASSWORD=gamepassword