Fix flake8 code style issues

- Remove unused imports (re, List, Optional, os, pytest)
- Fix line length violations by breaking long lines
- Add noqa comments for necessary E402 violations in app.py
- All code now passes flake8 with max-line-length=100

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: sandeeptadanow