Remove test artifacts and update gitignore

Co-authored-by: devedse <2350015+devedse@users.noreply.github.com>

Author: Copilot

.gitignore

@@ -409,4 +409,6 @@ DeveMazeGeneratorCore.Coaster3MF/_rels/
 
 # Generated output files from testing
 DeveMazeGeneratorCore.Coaster3MF/maze_coaster_*.3mf
-DeveMazeGeneratorCore.Coaster3MF/maze_coaster_*.png
+DeveMazeGeneratorCore.Coaster3MF/maze_coaster_*.png
+# Test output images
+/*.png