PB.Validate runs the upstream
protovalidate conformance suite
with scripts/run_protovalidate_conformance.sh, which needs Go to build the
harness and buf to rebuild the descriptor fixtures.
Expected failures are tracked in
test/fixtures/protovalidate_conformance/expected_failures.yaml. At the pinned
upstream bufbuild/protovalidate commit, the current baseline passes all cases:
PASS (failed: 0, skipped: 0, passed: 2872, total: 2872)