#118/#121: the speed fader and the formation editor under a mouse

Both read raw touches, and the project no longer turns clicks into them - the
same routing gap #93 fixed in the research tree. The boost was unreachable on
a desktop and the formation could not be rearranged at all.

Wrappers over the same press/drag logic in each case, never a second
implementation, so the touch and mouse paths cannot drift apart. The wheel
replaces the pinch in the formation editor: a mouse has no second finger, and
zoom is the other half of what that panel does.

The fader gets first refusal on a mouse press in GameController, so dragging
the boost does not also pan or zoom the world behind it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ui/SpeedFader.gd

@@ -77,17 +77,45 @@ func _blocked_by_modal() -> bool:
 	return false
 
 
+# #118: the same fader, driven by a mouse.
+#
+# The project used to set emulate_touch_from_mouse, which handed every raw
+# touch handler a synthetic touch per click; with that gone this control was
+# inert on a desktop and there was no other way to reach the boost. Written
+# as thin wrappers over the touch path rather than as a second
+# implementation, so the two cannot drift - the same mistake #93 fixed in
+# the research tree.
+const MOUSE_TOUCH_INDEX: int = -2
+
+
+func handle_mouse_button(event: InputEventMouseButton) -> bool:
+	if event.button_index != MOUSE_BUTTON_LEFT:
+		return false
+	return _press(event.pressed, event.position, MOUSE_TOUCH_INDEX)
+
+
+func handle_mouse_motion(event: InputEventMouseMotion) -> bool:
+	if active_touch_index != MOUSE_TOUCH_INDEX:
+		return false
+	_update_from_local(event.position - global_position)
+	return true
+
+
 func handle_touch(event: InputEventScreenTouch) -> bool:
-	var local: Vector2 = event.position - global_position
-	if event.pressed:
+	return _press(event.pressed, event.position, event.index)
+
+
+func _press(pressed: bool, at: Vector2, index: int) -> bool:
+	var local: Vector2 = at - global_position
+	if pressed:
 		if not visible or active_touch_index != -1 or _blocked_by_modal():
 			return false
 		if not Rect2(Vector2.ZERO, size).has_point(local):
 			return false
-		active_touch_index = event.index
+		active_touch_index = index
 		_update_from_local(local)
 		return true
-	if event.index != active_touch_index:
+	if index != active_touch_index:
 		return false
 	active_touch_index = -1
 	queue_redraw()