[AlexiAxAxA]

Purpose

Prepare the five Open Crate libraries and a thin opencrate facade for a coordinated crates.io release. The facade lets consumers use one dependency; individual oc-* packages remain available.

Changes

• Add publication metadata and versioned path dependencies.
• Add opencrate re-exports for the five libraries.
• Update the lockfile and export inventory. No core Rust implementation or frozen fixture changed.

Validation

• cargo check --locked --workspace --offline passed.
• cargo publish -p oc-policy --dry-run and cargo publish -p oc-crypto --dry-run passed; neither uploaded.
• Local candidate content check: zero findings; all six package lists include README and the custom license.
• Registry API returned 404 for all six exact package names before publication.

Remaining release gates

• Hosted Linux/Windows CI on this PR.
• Review package archives and custom license once more.
• Publish in dependency order: oc-policy, oc-crypto, oc-format, oc-protocol, oc-engine, opencrate. Verify each dependent package after its dependencies appear in the registry.

This PR does not publish a crate.