Write the README, API reference, storage guide, examples, and support policy

## Outcome

Document one native datasource with standalone and Harper usage, clearly distinguishing implemented APIs from planned integration.

## Acceptance criteria

- Cover installation, native quick start, Harper setup, supported platforms/Node versions, errors, limits and lifecycle.
- Document schema/query capabilities, BM25 scores, pagination, highlighting, status and metrics.
- Explain apply versus durable commit versus reader visibility, opaque checkpoint publication, replay, local replica indexing, and rebuild.
- Document persistent local files, source-data-only backups, restore invalidation, initial fulltext unavailability, disk/merge/rebuild headroom and encryption/permissions.
- State that no rocksdb-js dependency or customer storage provider is required; remove hosted-storage examples and unsupported exports from release docs.
- Test examples against packed packages and qualified Harper versions.
- Document reproducible benchmark scopes, GitHub release comparisons, support/security policy, and Apache-2.0 licensing.

## 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)