encryptBytes(data: Uint8Array): Promise<Uint8Array>
Encrypt binary data with AES-256-GCM using compact binary format. Output: ENCB + version byte + 12-byte IV + ciphertext (with GCM auth tag). Overhead is only 33 bytes (vs ~76% bloat in the legacy text format).
data: Uint8Array
Promise<Uint8Array>