- 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 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
Created shared_constants.py module that loads constants from the
shared JSON file. Updated availability.py and booking.py to import
from this module instead of hardcoding values.
This ensures backend and frontend stay in sync with the same source
of truth for booking configuration.