removeDrawing method
Removes a drawing from the chart canvas.
Implementation
void removeDrawing(String id) {
final removed = _drawings.where((d) => d.id == id).toList();
if (removed.isNotEmpty) {
recordDrawingSnapshot();
_drawings.removeWhere((d) => d.id == id);
onDrawingRemoved?.call(id);
notifyListeners();
triggerAutoSave();
}
}