Summary

This PR adds real-time queue state streaming so clients can react immediately to queue membership and match creation events without polling.

• Adds GET /queue/:slug/stream as an SSE endpoint that emits queue_state updates with:
  • latest queue snapshot
  • current users in queue
  • optional match info (id, serverId) when a match is created
• Emits queueUpdate events on queue join and leave actions in queue route handlers.
• Emits queueUpdate with match_created payload when queue processing creates a match (with or without a selected server).
• Refactors repeated role detection into a shared getRequesterRole() helper in queue routes.
• Includes players_per_team in match creation payload for queue-driven matches.

Why

The frontend queue page and live hooks need push-based updates for queue activity and match transitions. SSE + queue events provide a simple, low-latency mechanism to keep clients in sync and reduce polling complexity.

Test plan

• Start API and connect to stream:
  • curl -N http://<api>/queue/<slug>/stream
• Join queue from another authenticated client and verify a queue_state event is received with incremented currentPlayers.
• Leave queue and verify a queue_state event is received with decremented currentPlayers.
• Fill queue to trigger match creation and verify stream emits queue_state with match.id and match.serverId (or null when no server assigned).
• Verify queue cleanup still works when last player leaves and no permission regression is introduced.
• Confirm existing queue endpoints (GET /queue/:slug, PUT /queue/:slug) continue to behave as before.