major refactor(game-modes): centralize scoring and turn handling

* Move common ball recording, scoring, and turn-switching logic into `BaseMode`
* Add hooks for mode-specific ball handling and turn behavior
* Simplify 8-ball and 9-ball modes to use `LastBallMode`
* Update Snooker to use the new ball-processing hooks
* Remove duplicated scoring and turn-management code

controllers/game/modes/9_ball.gd

@@ -1,54 +1,5 @@
-class_name Ball9 extends BaseMode
+class_name Ball9 extends LastBallMode
 
 
-func  _init() -> void:
-	pass
-
-func reap_ball(ball: Node3D) -> void:
-	super(ball)
-
-	if ball.name == "09_ball":
-		# TODO: 9 ball must not be be destroyed. Handle rule...
-		ball_states[ball.name]["is_foul"] = true
-
-func process_ball(ball: Node3D) -> void:
-	super(ball)
-
-	if ball.name == "09_ball":
-		# TODO: 9 ball must be sunk last. Handle rule...
-		ball_states[ball.name]["is_foul"] = true
-
-func handle_switch_user() -> void:
-	push_warning("Balls reaped: ", balls_reaped.size() )
-	push_warning("Balls sunk: ",   balls_sunk.size()   )
-	var is_player_1: bool   = "Player 1" == get_player()
-	var switch_player: bool = true
-
-	if not balls_reaped.is_empty():
-		for ball_name in balls_reaped:
-			if is_player_1:
-				player_1_points -= ball_states[ball_name]["points"]
-			else:
-				player_2_points -= ball_states[ball_name]["points"]
-
-		balls_reaped.clear()
-
-	if not balls_sunk.is_empty():
-		# TODO: Handle points, etc, insure 9-ball not sunk unless last.
-		# Insure we process stripped vs solid ball and apropriate points accordingly.
-		# ball_states[ball.name]["is_foul"] = true
-
-		switch_player = false
-		balls_sunk.clear()
-
-	if ball_states_finalized():
-		process_win_condition()
-		return
-
-	if switch_player:
-		Globals.game_state.switch_active_player()
-
-	turn_count += 1
-
-func process_win_condition() -> void:
-	pass
+func _init() -> void:
+	final_ball_name = "09_ball"