Detect pytest repos without a main.py

Pytest-only repos with no sentinel main.py now show up in the New Procedure picker on their own. The audit treats a leaf test_*.py next to pyproject.toml as enough signal to commit to the pytest framework.

• Added test_*.py / *_test.py as a procedure signal in the repo audit
• Defaulted detected pytest procedures to entry point "." (the package directory)
• Dropped the sentinel main.py from the Pytest Starter template