Verilator build for integration tb needs gcc 14 toolset on older hosts

Verilator --timing testbenches need coroutine support. On hosts whose default g++ is below v10 (e.g., GCC 8), source /opt/rh/gcc-toolset-14/enable first. Build with verilator --cc --exe --build --timing -j 2 -Wno-fatal -Wno-lint -Wno-style -Wno-TIMESCALEMOD --top-module integration_top --Mdir <dir> and run <dir>/Vintegration_top. Output ports appear as public C++ members readable after eval.