Release v6.51.0

What's Changed

• test: launch stub tools through sys.executable instead of bare python by @hernloh in #598
• fix(synth): anchor the area and cell-count log scrape to the top module by @hernloh in #599
• fix(mcp): validate the coverage tools' path overrides like the phys tools do by @hernloh in #597
• fix(discovery): follow symlinked artefact directories in the coverage walk by @hernloh in #600
• feat(hub): paint the graph pane's module nodes with the physical model's heat ramp by @hernloh in #602
• fix(xfail): grade a non-verdict failure as FAIL under an xfail marker by @hernloh in #601
• feat(elab): bounded max_parse_depth profile option for generated RTL by @hernloh in #603
• feat(test): --plusarg overrides for rb test by @hernloh in #604
• feat(test): --run-tag per-run artefact namespace for concurrent runs by @hernloh in #605
• chore(nvim): pin rtl-buddy-nvim at v0.3.0 by @hernloh in #607

Full Changelog: v6.50.0...v6.51.0