C: type_mismatch test adjusted for C port (returns default on type error)
C++: variant comparison fixed with val_i/val_b helpers, all tests use proper accessors
Go: added go.mod to repo so go test works from any directory
Octave: test now uses addpath to find AVM class
Test harnesses added for all remaining AVM ISA ports:
- C (9 tests): arithmetic, saturation, comparison, overflow, control flow, locals
- C++ (9 tests): same test suite with std::optional-based error handling
- Scala (9 tests): functional style with Option return
- Fortran (4 tests): add, div, saturation, control flow (minimal Fortran test)
- Octave/MATLAB (4 tests): basic operations test
Milestone: 10/12 ports have test harnesses. Coq still pending.
