Root cause: Result.New didn't mark single-value results as OK=true,
breaking Mount/ReadDir/fs helpers that used Result{}.New(value, err).
Also: data_test.go and embed_test.go updated for Options struct,
doc comments updated across data.go, drive.go, command.go, contract.go.
All tests green. Coverage 82.2%.
Co-Authored-By: Virgil <virgil@lethean.io>
Move source from go/core/ to root, tests from go/tests/ to tests/.
Module path dappco.re/go/core resolves cleanly — builds and tests pass.
Co-Authored-By: Virgil <virgil@lethean.io>