* 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.
* Replace `valid_end` with `is_foul` for invalid ball sinks
* Rename and centralize ball state tracking
* Add ball finalization and win-condition hooks
* Update turn switching to retain the player after valid sinks
* Apply negative points to reaped balls
* Add active-player indicator to the camera UI
* Emit active-player updates when the turn changes
