feat(gameserver): lazy startup, lifecycle management

[EisigesEis]

Summary

• Lazy start Ramsgate and Training Grounds on request.
• Fast matchmaking based on gameserver ready instead of timer (see env config).
• Track player gameserver assignment and live connections and retire idle empty server faster (see env config). Needs lifecycle callbacks with per-server token.
• Handle startup failures, timeouts, restarts and live adopting.

Testing

• Ramsgate, Training Grounds: Idle shutdown, lazy startup and then fully functional.
• Hunts do not shut down early but instead after configured timer. Especially escalations were problematic here bc touch-player keeping alive connection.
• Readiness timeouts and failed-start cleanup.

Future work

• Public mm allow adding players in airship.
• Maybe explicit mm signal when all players abort hunt to close faster.
• Reuse compatible aborted hunt servers when healthy and new mm of same hunt.