* math prompt improvements
* ignore brackets in complex_arithmetic results
* improve additional instruction in prompt of polynomial_equations
* more strict tests for score_answer in polynomial_equations
* simplify special reward handling
* fix test_intermediate_integration
* fix sokoban dataset
* add common dataset score_answer consistency test
This commit introduces a new dataset for complex number arithmetic operations:
- Implements ComplexArithmeticDataset for generating complex number problems
- Supports addition, subtraction, multiplication, and division operations
Part of the algebra tasks collection in reasoning-gym.