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/ui_controls/camera/camera_controller.tscn

@@ -0,0 +1,65 @@
+[gd_scene load_steps=3 format=3 uid="uid://w3vh1gj6t2k2"]
+
+[ext_resource type="Script" uid="uid://bpf107mmjiswh" path="res://scenes/ui_controls/camera/camera_controller.gd" id="1_mvpa7"]
+
+[sub_resource type="LabelSettings" id="LabelSettings_mvpa7"]
+font_size = 24
+
+[node name="camera_controller" type="Control"]
+layout_mode = 3
+anchors_preset = 12
+anchor_top = 1.0
+anchor_right = 1.0
+anchor_bottom = 1.0
+offset_top = -68.0
+offset_bottom = -68.0
+grow_horizontal = 2
+grow_vertical = 0
+script = ExtResource("1_mvpa7")
+
+[node name="margin_container" type="MarginContainer" parent="."]
+layout_mode = 1
+anchors_preset = 10
+anchor_right = 1.0
+offset_bottom = 69.0
+grow_horizontal = 2
+theme_override_constants/margin_left = 10
+theme_override_constants/margin_top = 5
+theme_override_constants/margin_right = 10
+
+[node name="vbox" type="VBoxContainer" parent="margin_container"]
+layout_mode = 2
+
+[node name="hbox" type="HBoxContainer" parent="margin_container/vbox"]
+layout_mode = 2
+size_flags_vertical = 3
+
+[node name="hbox2" type="HBoxContainer" parent="margin_container/vbox/hbox"]
+layout_mode = 2
+size_flags_horizontal = 10
+
+[node name="prev_bttn" type="Button" parent="margin_container/vbox/hbox/hbox2"]
+z_index = 1
+layout_mode = 2
+focus_mode = 0
+mouse_default_cursor_shape = 2
+text = "<Prev>"
+flat = true
+
+[node name="label" type="Label" parent="margin_container/vbox/hbox/hbox2"]
+layout_mode = 2
+text = "  Camera  "
+label_settings = SubResource("LabelSettings_mvpa7")
+horizontal_alignment = 1
+vertical_alignment = 1
+
+[node name="next_bttn" type="Button" parent="margin_container/vbox/hbox/hbox2"]
+z_index = 1
+layout_mode = 2
+focus_mode = 0
+mouse_default_cursor_shape = 2
+text = "<Next>"
+flat = true
+
+[connection signal="pressed" from="margin_container/vbox/hbox/hbox2/prev_bttn" to="." method="_on_prev_bttn_pressed"]
+[connection signal="pressed" from="margin_container/vbox/hbox/hbox2/next_bttn" to="." method="_on_next_bttn_pressed"]