add-propagator-chirho

Add a new propagator to propagators-chirho: $ARGUMENTS

Instructions

1. Analyze the requested propagator type and its bidirectional semantics
2. Determine if it fits existing macros:
   • ternary_propagator_chirho! - for a op b = c patterns
   • binary_propagator_chirho! - for unary a = b patterns
   • comparison_propagator_chirho! - for max/min style patterns
3. Add the propagator to src/propagator_chirho.rs following existing patterns
4. Add corresponding method to ConstraintSystemChirho in src/constraint_system_chirho.rs
5. If arena feature is used, add to src/arena_chirho.rs as well
6. Add unit tests for the new propagator
7. Update CHANGELOG.md with the new propagator under [Unreleased]
8. Run tests to verify: cargo test