web: property suite 4/4 on the external corpus (definitional absolutes join the relations); de-flaked test_b2b

web: sync-guard gradient repair, FineWeb-Edu hardcoded (parquet /data streaming), dispatch-optimized backward (bit-identical), IEEE-754 oracle + corpus mutation tests, TEST_RESULTS.md

Web demo: metamorphic property tests (no-oracle correctness checks)