Multiple simultaneous lobbies (parallel cup instances)

Description

Currently only one cup can run at a time on a single server instance. For beta with more concurrent players, multiple lobbies must be able to run simultaneously in separate game instances on the same JVM.

Acceptance Criteria

• A player joining the server is routed to an available lobby (one with space, waiting for players) or a new lobby is created
• Each lobby is an isolated GameInstance in Minestom with its own EntityManager and phase lifecycle
• Cup/map data is shared (read-only) between instances — no data duplication
• Maximum concurrent instances is configurable (default: 4 per server)
• Players in different instances cannot see, hear, or collide with each other
• When an instance completes its cup, it is cleaned up and its slot becomes available
• Load test verifies 4 parallel instances × 5 players = 20 total players within tick budget

Technical Details

• New LobbyManager or InstanceRouter in server module
• Minestom supports multiple InstanceContainer objects — use one per lobby
• EntityManager is per-instance, not global

Dependencies

• "Load-test ECS game loop" (Alpha) results should guide the per-instance player cap

Estimate

XL

Start in the server module and review the existing game lifecycle, then inspect Minestom's InstanceContainer and per-instance EntityManager model. Use the “Load-test ECS game loop” results to guide the player cap and run the required parallel-instance load test. Done means the acceptance criteria are verified, including routing, isolation, cleanup, configuration, and 4-instance performance.