rustdv-runner

The regression manager (design-doc D2.4, §4.5): port of cocotb's RegressionManager. Owns the test registry (populated at link time by #[rustdv::test]), runs tests sequentially, applies timeouts, scores panics/errors vs. expectations, prints the summary table, and provides the simulator entry point.

Bootstrap deviation from D3.2 (STATUS.md): instead of exporting cocotb's libpygpi entry symbols, the testbench cdylib is loaded as a plain VPI module (vvp -M<dir> -m<name>): rustdv::vpi_bootstrap!() exports vlog_startup_routines, whose startup routine registers a cbStartOfSimulation callback that kicks off the regression.