B bild does not propagate langdeps from dep-commented modules through hsGraph

When module A depends on module B (via -- : dep comment), and module B has langdeps (via -- : dep comments), bild's hsGraph tracks the relationship but doesn't propagate B's langdeps to A's build. This causes builds to fail because A's dependencies can't find B's required packages like sqlite-simple. The transitive deps logic seems to only work for automatically detected imports, not for module dependencies declared via comments.