feat: introduce Stop N Go game mode with phase management, dynamic arena setup, and goal tracking.

scripts/managers/goals_cycle_manager.gd

@@ -93,7 +93,7 @@ func _process(delta):
 # Global Match Control
 # =============================================================================
 
-func start_match(duration_seconds: float):
+func start_match(duration_seconds: float, start_cycles: bool = true):
 	"""Start the global match timer. Called by server when game starts."""
 	match_duration = duration_seconds
 	global_match_timer = duration_seconds
@@ -103,8 +103,9 @@ func start_match(duration_seconds: float):
 	
 	if multiplayer.is_server():
 		rpc("sync_match_start", duration_seconds)
-		# Also start the first cycle
-		start_cycle()
+		# Only start the first cycle if requested
+		if start_cycles:
+			start_cycle()
 
 func _on_match_end():
 	"""Called when global match timer reaches zero - game over!"""

scripts/managers/stop_n_go_manager.gd

@@ -9,8 +9,8 @@ signal player_penalized(player_id: int)
 
 enum Phase {GO, STOP}
 
-const GO_DURATION: float = 12.0
-const STOP_DURATION: float = 6.0
+const GO_DURATION: float = 8.0
+const STOP_DURATION: float = 4.0
 const REQUIRED_GOALS: int = 2
 
 var current_phase: Phase = Phase.GO