- Introduced exact arithmetic with support for large integers and fractions in `exact.gd`, `big_integer.gd`, and `exact_value.gd`.
- Implemented a comprehensive test suite in `test_exact_math.gd` to validate arithmetic operations against expected results.
- Added a README in `math` directory to document the exact arithmetic system and its usage.
- Ensured that all arithmetic operations maintain precision without floating-point errors, using a custom representation for large numbers.
- Included methods for encoding and decoding exact values for serialization.
- Introduced `quantity_math.gd` for arithmetic operations including allocation, normalization, and accumulation of quantities without scene tree dependencies.
- Created `entity_catalog.gd` to manage entity definitions, groups, and event indexes, ensuring separation from simulation state and UI.
- Implemented `item_presentation.gd` for read-only projections of simulation state, handling amounts and unlock conditions for UI elements.
- Updated `civilization_evolution.gd` and `civilization_state.gd` to utilize new quantity math functions, improving code clarity and maintainability.
- Enhanced tests in `test_quantity_catalog.gd` to validate new functionality and ensure correctness of mathematical operations.
- Revised documentation to reflect changes in module structure and functionality.
Kirill