Delete old bot versions in src/old

The bot, tests and .exe build use none of them. They stay in Git
history (902ff93) if the old logic is ever needed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pyproject.toml

@@ -18,5 +18,4 @@ dev = [
 ]
 
 [tool.pytest.ini_options]
-# src/old/test_docai.py and src/old/test_pdf.py are old Document AI scripts, not tests
 testpaths = ["tests"]