Add LobbyAnnouncer with beta broadcasts

Introduce a LobbyAnnouncer module that periodically broadcasts a MiniMessage announcement during the LOBBY state. The new class (game/modules/LobbyAnnouncer.kt) schedules broadcasts every 30 seconds when the new config flag game.beta is true and provides start/stop lifecycle methods. Integrate the announcer into the main plugin (SpeedHG.kt) by adding a lobbyAnnouncer field and starting it during initialization. Also update config.yml to add game.beta: true and change teams.enabled from true to false.

src/main/resources/config.yml

@@ -4,6 +4,7 @@
 #
 
 game:
+  beta: true
   min-players: 2
   lobby-time: 60
   invincibility-time: 60
@@ -27,7 +28,7 @@ lunarclient:
   variantName: 'SpeedHG - Solo'
 
 teams:
-  enabled: true
+  enabled: false
   max-size: 2
 
 recraftNerf: