Introduce civTraits data structure with 8 traits (scientific, industrious,
commercial, philosophical, zealous, mercantile, pioneering, wealthy) that
provide science/gold/shield multipliers, starting gold, and starting
technologies. Assign each opponent a trait in opponents.json.
- Apply trait bonuses to starting gold and grant starting techs during
game creation in CivilizationLogic
- Route trait multipliers into cityYields for science, gold, and production
- Add a leader detail panel to the setup screen showing name, trait name,
and description, updated live when selecting leaders
- Add validation for civTraits in CivilizationRules (multipliers positive,
starting techs valid, etc.)
- Add verification tests for trait application and city yield multipliers
- Nudge unit sprite position 5px down for better tile alignment