Function wrapKeyForRecipient

wrapKeyForRecipient(params: WrapKeyParams): Promise<WrappedKey>
Wraps a key for an OFFLINE recipient via X3DH envelope.

Flow: X3DH initiation against the recipient's bundle → derive a one-time wrapping key → AES-256-GCM encrypt the target key.

───────────────────────────────────────────────────────────── Security properties ─────────────────────────────────────────────────────────────
- Forward secrecy at handshake: the ephemeral X25519 key is fresh per envelope; the wrapping key cannot be recomputed from long-lived keys alone.
- Offline delivery: the recipient unwraps whenever they next come online, using their persisted pre-key material.
- MITM defense: the recipient's SPK signature is verified inside initiateX3DH.
Parameters
- params: WrapKeyParams
Returns Promise<WrappedKey>
Example
```
// Group owner delivers the group key to each member:
const wrapped = await wrapKeyForRecipient({
  keyBytes: groupKey, recipientBundle: memberBundle,
  myIdentity: ownerIdentity,
  contextSalt: new TextEncoder().encode(groupId),
  info: 'me2em/crypto/v1/group-key',
});
// upload `wrapped` — the server can store but not open it
```
- Defined in packages/crypto/src/envelopes/key-wrapping.ts:81