v0.3.1: Add PaperScout digest example script with configurable parameters

- Create examples/run_paperscout_digest.py demonstrating complete workflow
- Exclude examples directory from ruff lint checks for flexible imports
- Remove temporary test script (scripts/test_paperscout_email.py)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>