Clean up test files and improve gitignore patterns

Co-authored-by: mmcky <8263752+mmcky@users.noreply.github.com>

Author: Copilot

.gitignore

@@ -10,4 +10,7 @@ dask-worker-space
 lectures/sine_wave.py
 lectures/mathfoo.py
 lectures/mod.py
-lectures/test.py
+lectures/test.py
+lectures/foo.py
+lectures/*.txt
+lectures/*.csv