vta-support

Shared mid-layer services for the VTA, extracted from vta-service so the subsystem crates can depend on them without depending on the whole service.

• contexts — trust-context storage (the BIP-32 key-hierarchy roots).
• seal — the sealed-transfer producer-side seal helper.
• sealed_nonce_store — the sealed-bootstrap anti-replay nonce store.

Each is a self-contained near-leaf, depending only on vti-common, vta-config, vta-keyspaces, and vta-sdk. vta-service re-exports each as crate::<module>, so existing call sites are unchanged.

Part of the Verifiable Trust Infrastructure workspace. Apache-2.0.