- Remove EUR_TRADE_MIN, EUR_TRADE_MAX, PREMIUM_PERCENTAGE from shared_constants.py
- Remove eurTradeMin, eurTradeMax, premiumPercentage from shared/constants.json
- Update validate_constants.py to not require removed fields
- Update seed.py and seed_e2e.py to use defaults if fields don't exist
- Update tests to handle missing constants gracefully
- Add seed_pricing_config() function to seed.py
- Seed initial values from shared/constants.json
- Add seeding to seed_e2e.py for E2E tests
- Add tests for seeding functionality
- Add ruff as dev dependency
- Configure ruff in pyproject.toml with strict 88-char line limit
- Ignore B008 (FastAPI Depends pattern is standard)
- Allow longer lines in tests for readability
- Fix all lint issues in source files
- Add Makefile targets: lint-backend, format-backend, fix-backend