Refactor game mode scoring and win conditions

* Add overridable hooks for sunk/reaped ball handling and turn behavior.
* Implement default scoring and game-over messaging across game modes.
* Add pretty game mode names for win-condition messages.
* Update Free Ball, Last Ball, and Snooker modes to return win-condition messages.
* Move the reset button lookup to the scene root for multiplayer setup.
* Move camera controller scene to shared base UI. Move parts of it to new game_data UI node.
* Add commented test state generation for end-state testing.

scenes/data/game_data.gd

@@ -41,6 +41,18 @@ var SelectedGameMode: GameModeType = GameModeType.FREE_BALL
 func _init() -> void:
 	Globals.game_data = self
 
+func get_mode_pretty() -> String:
+	match game_mode:
+		"8ball":
+			return "8-Ball"
+		"9ball":
+			return "9-Ball"
+		"snooker":
+			return "Snooker"
+		"freeball":
+			return "Free Ball"
+		_:
+			return ""
 
 @rpc("authority", "reliable")
 func set_game_address(address: String) -> void: