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/base_mode.gd

@@ -28,11 +28,74 @@ var BALL_STATE: Dictionary  = {
 }
 
 
-func  _init() -> void:
+func _process_reaped_balls(player: String) -> void:
+	for ball_name in balls_reaped:
+		_add_points(player, -ball_states[ball_name]["points"])
+
+	balls_reaped.clear()
+
+func _process_sunk_balls(player: String) -> void:
+	for ball_name in balls_sunk:
+		_add_points(player, ball_states[ball_name]["points"])
+
+	balls_sunk.clear()
+
+func _record_ball(
+	ball: Node3D,
+	state_key: String,
+	tracker: Array
+) -> void:
+	tracker.append(ball.name)
+
+	ball_states[ball.name]["turn"]    = turn_count
+	ball_states[ball.name]["player"]  = get_player()
+	ball_states[ball.name][state_key] = true
+
+func _add_points(player: String, amount: int) -> void:
+	if player == "Player 1":
+		player_1_points += amount
+	else:
+		player_2_points += amount
+
+
+func get_player() -> String:
+	return (
+		"Player 1"
+			if Globals.game_data.client1 ==
+				Globals.multiplayer_data.current_turn_player_id
+			else
+		"Player 2"
+	)
+
+# NOTE: Override when a mode doesn't awards points for sunk balls.
+func score_sunk_balls() -> bool:
+	return true
+
+# NOTE: Override when a mode shouldn't keep the player's turn after a legal sink.
+func keep_turn_after_sink() -> bool:
+	return true
+
+# NOTE: Override when a modehas extra processing such as
+#       checking if solid or striped ball.
+func on_ball_reaped(_ball: Node3D) -> void:
 	pass
 
+# NOTE: Override when a modehas extra processing such as
+#       checking if solid or striped ball.
+func on_ball_sunk(_ball: Node3D) -> void:
+	pass
+
+
+func reap_ball(ball: Node3D) -> void:
+	_record_ball(ball, "reaped", balls_reaped)
+	on_ball_reaped(ball)
+
+func process_ball(ball: Node3D) -> void:
+	_record_ball(ball, "sunk", balls_sunk)
+	on_ball_sunk(ball)
+
 func generate_ball_states() -> Dictionary:
-	var state := {}
+	var state: Dictionary = {}
 
 	for i: int in range(1, 16):
 		var ball_name    = "%02d_ball" % i
@@ -41,6 +104,26 @@ func generate_ball_states() -> Dictionary:
 
 	return state
 
+func handle_switch_user() -> void:
+	push_warning("Balls reaped: ", balls_reaped.size() )
+	push_warning("Balls sunk: ",   balls_sunk.size()   )
+
+	var player: String      = get_player()
+	var no_sunk_balls: bool = balls_sunk.is_empty()
+
+	_process_reaped_balls(player)
+	if score_sunk_balls():
+		_process_sunk_balls(player)
+
+	if ball_states_finalized():
+		process_win_condition()
+		return
+
+	if no_sunk_balls or not keep_turn_after_sink():
+		Globals.game_state.switch_active_player()
+
+	turn_count += 1
+
 func ball_states_finalized() -> bool:
 	for ball_state in ball_states.values():
 		if ball_state["reaped"] or ball_state["sunk"]:
@@ -52,28 +135,3 @@ func ball_states_finalized() -> bool:
 
 func process_win_condition() -> void:
 	assert(false, "This method needs to be overridden...")
-
-func get_player() -> String:
-	return                                                                           \
-		"Player 1"                                                                   \
-	if                                                                               \
-		Globals.game_data.client1 == Globals.multiplayer_data.current_turn_player_id \
-	else                                                                             \
-		"Player 2"
-
-func reap_ball(ball: Node3D) -> void:
-	balls_reaped.append(ball.name)
-
-	ball_states[ball.name]["turn"]   = turn_count
-	ball_states[ball.name]["player"] = get_player()
-	ball_states[ball.name]["reaped"] = true
-
-func process_ball(ball: Node3D) -> void:
-	balls_sunk.append(ball.name)
-
-	ball_states[ball.name]["turn"]   = turn_count
-	ball_states[ball.name]["player"] = get_player()
-	ball_states[ball.name]["sunk"]   = true
-
-func handle_switch_user() -> void:
-	assert(false, "This method needs to be overridden...")