Epic: Qualify, document, package, and release @harperfast/fulltext

## Outcome

Make the native-only wrapper reproducible, supportable, and qualified for standalone and Harper use.

## Acceptance criteria

- Test native filesystem lifecycle, checkpoint publication, crash/recovery, concurrency, errors, and the real Harper path.
- Compare standalone native wrapper, Harper without fulltext, and Harper with a native derived index; distinguish engine and product measurements.
- Keep versioned compatible benchmark history in GitHub across releases, with PR correctness smoke and controlled scheduled/release profiles.
- Ship tested platform prebuilds, Node support matrix, provenance, install smoke, changelog, license and support/security policies.
- Document native setup, Harper integration, rebuild/restore, disk headroom, filesystem permissions/encryption, and actionable failures.
- Remove unsupported hosted storage exports and dependencies before release; preserve old experiment results as historical evidence.

## Design

[Native Tantivy storage and Harper derived indexes](https://github.com/HarperFast/fulltext/blob/codex/native-storage-design/docs/native-storage-integration.md). Native Tantivy files are the only delivery target for standalone use and Harper. Proposed APIs and integration gates are not claims of completed implementation.

Comment generated by kAIle (GPT-6)